Bench-scale Flotation Experiments Research Articles

Application of inverse gas chromatography to bench scale flotation of sulphide ore

ABSTRACT Inverse gas chromatography (IGC) is receiving increasing attention due to its high precision and ease of application in determining various characteristics of a wide variety of materials of different shapes and morphologies. This study details an experimental investigation into the application of the IGC technique to the flotation of sulphide minerals. Rather than giving the surface energy, the trends associated with the various concentrates and tailings are described. Bench-scale flotation experiments of a nickel-copper sulphide ore were conducted in a Denver flotation cell. The IGC analyses were carried out on the timed concentrates, as well as on the final tailings, in order to evaluate the correlation between surface energetics and the flotation response of the ore particles. The results indicated that the floatability of the concentrates was directly related to the surface energy of the particles. Both dispersive and specific components of surface free energy increased by increasing the necessary time for the particles to be floated, which was consistent with the obtained values for the work of adhesion to water. However, the flotation response of the tailings was not consistent with the expectations from the surface energy value. The significance of the sample composition, particle size distribution, and their consequences in surface energy-flotation response relationship were also observed.

Froth flotation separation of lepidolite ore using a new Gemini surfactant as the flotation collector

Comparison diagram of flotation behavior of lepidolite by new Gemini collector HBDB and traditional monomolecular collector DA. • A novel amine-based Gemini surfactant HBDB was synthesized in our lab. • HBDB was introduced as an efficient collector of lepidolite flotation. • HBDB has better collecting ability and selectivity than traditional collector DA. • Using less dosage HBDB obtained a higher quality lepidolite concentrate. The global lithium supply and demand in this century is accelerated by the energy transition from carbon-based fossil fuels to renewable energy where electrical energy storage and electric vehicles heavily depend on the lithium-ion battery. The lepidolite is one of the main resources for extracting lithium, and it is usually enriched by froth flotation separation technology. However, the traditional lepidolite collector is monomer surfactant with only a single hydrophobic group and hydrophilic group, which usually leads to the low flotation separation efficiency. Therefore, to achieve the flotation separation of lepidolite ore more efficiently, in this work, an amine-based Gemini surfactant, hexanediyl-α, ω-bis (Dimethyldodecylammonium bromide) (HBDB), was synthesized, and compared with the conventional single molecule collector dodecylamine (DA). The experimental results show that the optimum pH value of flotation is 3, and the optimum dosage of HBDB and DA are 150 g/t and 300 g/t respectively. In bench-scale flotation experiments, compared with the conventional monomer DA collector (350 g/t), the Gemini HBDB with only 1/2 dosage of DA (175 g/t) increased the recovery of lepidolite by 16.18%. Economic calculation for a lepidolite ore plant, 1500 t/d, demonstrating that using Gemini HBDB can gain more about $ 8.2 million USD per year than using traditional unimolecular DA. Accordingly, this study provides a new and highly efficient collector for the flotation separation of lepidolite ore.

Selective flotation separation of apatite from calcite using hydrolytic polymaleic anhydride as an eco-friendly and efficient depressant

Flotation separation of apatite from calcite has always been challenging because of the similar surface physicochemical properties of apatite and calcite. In this study, hydrolytic polymaleic anhydride (HPMA) was used as an eco-friendly and efficient inhibitor to enhance the flotation separation efficiency of apatite from calcite. The depression performance of HPMA on these minerals was explored using microflotation experiments and bench-scale flotation tests. The adsorption behavior and inhibiting mechanism of HPMA were investigated using zeta potential analysis, surface wettability analysis, adsorption amount measurements, and X-ray photoelectron spectroscopy. Microflotation experiments revealed that HPMA presented selectively inhibitory action on calcite flotation and negligible effect on apatite flotation. The bench-scale flotation experiments demonstrated that effective flotation separation of apatite from calcite can be achieved using HPMA as the depressant and sodium oleate (NaOl) as the collector. Under these experimental conditions, an apatite concentrate with P2O5 grade of 36.21 ± 0.71% and recovery of 81.18 ± 1.84% was obtained. Mechanism investigation indicated that HPMA was strongly adsorbed on the calcite surface via chemical reactions between the carboxyl groups of HPMA and activated Ca sites of calcite. This significantly hindered subsequent NaOl adsorption. By contrast, the amount of HPMA physisorbed on the apatite surface was significantly smaller, and its effect on the subsequent adsorption of NaOl on the apatite surface was limited. Accordingly, the selective depression of calcite flotation and efficient flotation separation of apatite from calcite were achieved. In summary, HPMA can be used as a potentially green and highly efficient inhibitor in the flotation separation of apatite from calcite.

Influence of surface dissolution on reagents’ adsorption on low-grade phosphate ore and its flotation selectivity

A preliminary study was conducted on the Hallimond tube to find routes for the direct flotation of fluorapatite. Carboxymethylcellulose-sodium oleate and sodium alginate-sodium oleate were the most promising depressant-collector combinations. Apatite recovery exceeded 95%. Conversely, replication of these findings in the mechanical flotation cell proved to be different. The results show a flotation of the calcite, while the fluorapatite remains in the tailings. Grades of 27.63% P2O5 with a recovery of 69.9% and 28.22% P2O5 with a recovery of 73.93% were obtained in the non-floated fraction using 1500 g/t of sodium oleate and 25 g/t of sodium alginate and carboxymethylcellulose as depressants, respectively.The effects of metal ions on the flotation behavior of fluorapatite, calcite, and quartz were investigated through micro-flotation tests and bench-scale flotation experiments. The findings were further elucidated by dissolution study, zeta potential measurements, and FTIR analyses. The results demonstrated that pulp water containing large amounts of Ca2+, Mg2+, and Fe3+ directly influences the performance of apatite flotation. Fluorapatite recovery substantially dropped from 97.27% in deionized water, reaching values below 11.11% at alkaline pH. These ionic species interfere in the interfacial processes and perturb selective adsorption. Ca2+ ions favor the precipitation of CaCO3, hence forms a coating on the apatite surface, rendering it unavailable for NaOL chemisorption. Ca2+, Mg2+, and Fe3+ complex with the reagents and the precipitates adsorb onto the minerals’ surfaces, impairing their floatability. Also, their presence activates the quartz surface, increasing its recovery. Zeta potential curves overlap, implying a similar build-up of negative charge on the three mineral surfaces. The most intense peaks in FTIR spectra indicated more adsorption, suggesting that the detrimental species Ca2+, Mg2+, Fe3+ must be involved in adsorption mechanisms and explain flotation trend change.

Separation of wolframite ore by froth flotation using a novel “crab” structure sebacoyl hydroxamic acid collector without Pb(NO3)2 activation

In this study, a new hydroxamic-acid molecule - sebacoyl hydroxamic acid (SHA) was synthesized and characterized. It was the first time that SHA with dual hydroxamic acid groups of “crab” structure was used as a collector for wolframite flotation, and its collecting ability was compared with the traditional collector benzohydroxamic acid (BAH) in the presence or absence of lead ions. In micro-flotation experiments, the wolframite recovery using 4 × 10−4 mol/L SHA collector alone was 30% higher than that using 4 × 10−4 mol/L BHA collector and 1 × 10−4 mol/L Pb(NO3)2 activator. The results of bench-scale flotation experiments showed that the WO3 recovery of wolframite concentrate with 180 g/t SHA was 10.05% higher than that with 360 g/t BHA and 300 g/t Pb(NO3)2. Therefore, using SHA collector with “crab” structure for wolframite flotation can not only improve the separation index at a low dosage, but also eliminate the use of Pb(NO3)2.

Utilization of polyepoxysuccinic acid as the green selective depressant for the clean flotation of phosphate ores

In flotation, the application of some flotation reagents may cause serious water pollution and damage the ecological environment and human health. Large consumption of flotation reagents also restricts the sustainable production of mines. Therefore, the development and application of environmentally friendly and economical flotation reagents are essential for the sustainable production of phosphate ores and phosphate fertilizer. In this work, a non-nitrogen and phosphorus-free green, economical and environmentally friendly reagent, polyepoxysuccinic acid was used to evaluate its selective inhibition on calcite during apatite flotation. Micro-flotation experiments were used to investigate the floatability of the two minerals. Bench-scale flotation experiments were used to verify the efficiency of industrial application of polyepoxysuccinic acid in the flotation phosphate ores. Depression mechanism of polyepoxysuccinic acid was revealed through zeta potential measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscope. The flotation separation of apatite and calcite can be achieved with polyepoxysuccinic acid using sodium oleate as collector. Bench-scale flotation experiments show that a good flotation index with a P2O5 grade of 32.74% and a recovery of 84.82% can be obtained at a depressant dosage of 80 g/t. Mechanism experiment proved polyepoxysuccinic acid had a stronger adsorption on calcite than apatite. The adsorption of polyepoxysuccinic acid on calcite was mainly chemical adsorption through the chelation of its carboxyl group and calcium atoms. Therefore, this work provides a clean and economic reagent for the sustainable production of phosphate ores and phosphate fertilizer, which is of great significance for the sustainable development of clean mines.

"Umbrella" Structure Trisiloxane Surfactant: Synthesis and Application for Reverse Flotation of Phosphorite Ore in Phosphate Fertilizer Production.

Phosphorite is generally used in the manufacture of phosphate fertilizer and plays a vital role in the development of agricultural and food production. Nonetheless, how to obtain phosphorite concentrates efficiently and sustainably has become an urgent problem. In this study, a newly designed trisiloxane surfactant, N-(2-Aminoethyl)-3-aminopropyltrisiloxane (AATS), has been prepared and utilized as an emerging collector for reverse flotation of phosphorite ore. Its collecting ability was compared with the conventional surfactant 1-dodecamine (DDA). In the collector concentration tests, AATS with lower concentrations showed stronger collecting ability for quartz. In the pH tests, AATS always performed better than DDA in the acidic or alkaline condition. In bench-scale flotation experiments, the P2O5 recovery of phosphorite concentrates with 150 g/t AATS was 10.77% higher than that with 300 g/t DDA, which proved that AATS can be applied to the sustainable production of phosphorite concentrates. For a 4000 t/d phosphorite ore processing plant, the profit could be increased 7,014,702.07 USD every year by using AATS as the collector. Therefore, this work provides a promising approach to enhance the production efficiency of phosphate fertilizer and to promote the sustainable development of agriculture.

Investigation of Copper Recovery from a New Copper Deposit (Nussir) in Northern-Norway: Thionocarbamates and Xanthate-Thionocarbamate Blend as Collectors

Norway has newly seen an upsurge of interest in exploiting its mineral deposits influenced by fresh Government focus and survey support for previously under-prospected areas. One of the major areas of interest is a huge copper deposit, operated by Nussir ASA, located in the Repparfjord tectonic window in the Caledonides of west Finnmark. The latest mineral resource estimation is from July 2014, which states that Nussir consists of 5.8 million tonnes of indicated resources and 60.2 million tonnes of inferred resources, giving 66 million tonnes of copper ore. This paper represents the first study on processing characteristics of this ore to date. Our parallel studies using xanthates and dithiophosphates as collectors for Nussir ore flotation examined the grade and recovery of copper, silver, gold, and platinum group (PGM) minerals. Therefore, in this subsequent study, a chelating agent n-Butoxycarbonyl-O-n-butyl thionocarbamate (BBT) is used as a collector and it was found that the recovery and grades of the economically interesting minerals are improved at as low as 2 × 10−5 M collector concentration. Zeta potential, Hallimond flotation and adsorption studies were initially performed in order to assess the selective interaction of BBT and its blend with SIBX (Sodium Isobutyl xanthate) on the three copper minerals of the ore. The bench scale flotation experiments were performed using mixtures of xanthate and thionocarbamate collectors of the Nussir ore and both the resulting copper recovery and grade employing these collector mixtures is observed to be 2–8% superior to the use of a single collector system. Additionally, the current study revealed that the metallurgical results are strongly influenced by the ratio of the collectors in the mixture and particularly the sequence of the collector addition.

Pyrrhotite oxidation and its influence on alkaline amine flotation

In the production of ground calcium carbonate (GCC) for the paper industry, pyrrhotite dramatically reduces the GCC brightness and the removal of pyrrhotite through froth flotation is essential. The present study aims to study the effect of pyrrhotite oxidation on flotation recoveries during typical GCC flotation (i.e. alkaline pH, CaCO3 saturation, amine collector). EDTA extraction and measurements of Eh (redox potential) showed a significant difference in pyrrhotite surface oxidation state when comparing exposure times of 40 and 60min, the latter being significantly more oxidised. Microflotation results show that when pyrrhotite is exposed to air extending for more than 5min at pH 8, the recoveries drop significantly. At higher pH, recoveries were generally low at all exposure times tested. Flotation recoveries showed strong correlation with zeta potential measurements. Bench scale flotation experiments on a sulphide bearing marble, confirmed that pyrrhotite oxidation significantly lower the GCC quality at low collector concentrations. By increasing the amine concentration, the flotation performance became independent of pH and exposure time.

Flotation of pyrrhotite and pyrite in saturated CaCO3 solution using a quaternary amine collector

In the production of ground calcium carbonate (GCC) for the paper industry, any colouring contaminants must be removed during processing (usually flotation) to achieve sufficient GCC brightness. Flotation of GCC feedstock is characterised by the presence of both particulate and dissolved calcite (CaCO3), an alkaline pH and the use of amine collectors. This paper investigates the possibility of removing pyrrhotite and pyrite, under these conditions. Microflotation results show that the recoveries are highly dependent on pH. Pyrrhotite recovery decreases dramatically when going from pH 8 to pH 10. Pyrite display high recoveries at pH 8 and 9, and lower recoveries at higher pH. Recoveries were dependent on conditioning time. Pyrite floats considerably faster than pyrrhotite at all pH levels investigated, whereas pyrrhotite seems to be slow floating and could benefit from prolonged flotation times. Compared to the saturated CaCO3 system, flotation recoveries decreased when using deionised water or CaCl2 solution. The flotation results could not be fully explained by zeta potential. Bench scale flotation experiments on a sulphide bearing marble, confirmed the microflotation results at low collector concentrations (i.e. 200g/t). By increasing the amine concentration, the flotation performance became independent of pH.

Flotation of oxidized zinc ore without desliming

To increase zinc recovery in the concentrate, this investigation performed mineralogical characterization, dispersion studies, bench and pilot-scale flotation experiments and an industrial flotation trial. The objective was to verify the flotation behavior of the silicate zinc ore (calamine type) in the presence of slimes, with the aid of dispersing agents. Characterization studies identified the major minerals in the flotation feed as hemimorphite (calamine), quartz and dolomite. Dispersion tests showed that enhanced dispersion of the particles in the pulp in the absence of reagents occured at a pH range between 8.5 and 12.0. Bench-scale flotation experiments were planned using the statistical tool of complete factorial design at two levels, replicated once. These experiments showed, and were confirmed at the pilot-plant scale, that higher doses of sodium sulfide and polymeric dispersant combined with sodium silicate favored a higher metallurgical recovery. At 6,800 g/t (218 oz/st) sodium sulfide and 6,992 g/t (224 oz/st) polymeric dispersing agent combined with sodium silicate, a zinc grade of 38.4% in the final concentrate was achieved, at an average metallurgical recovery of 72.4%. The industrial trial confirmed the pilot scale results, leading to zinc recovery of 76.1% and a 37.3% zinc grade in the concentrate.

Influence of particle size and reagent dosage on the performance of apatite flotation

Mineral particle size plays a significant role on the flotation process. The flotation performance (grade and recovery) of apatite particles in a complex carbonatite ore from Brazil was investigated in a flotation column as a function of particle size and reagent concentrations. Flotation feed samples were also mineralogically and chemically characterized. For the bench scale flotation experiments, the sample was fractioned into different size intervals. The experiments were conducted according to a factorial experimental design. The experimental data were analyzed using P 2O 5 grade/recovery curves, response surface methodology and canonical analysis. An optimum particle size was found under the experimental conditions studied. The P 2O 5 grade and recovery rates obtained with a particle size between 37 μm and 105 μm were simultaneously higher than those required industrially.

Quartz-feldspar separation for the glass and ceramics industries

Large reserves of feldspar ore exist in the Aegean region of Turkey. The main colored impurities in these ores are iron- and titanium-bearing minerals such as anatase, rutile, sphene and ilmenite. In this study, a potassium feldspar ore containing mainly quartz and coloring impurities was subjected to beneficiation tests involving magnetic-separation and flotation, which were applied either separately or in combination. Bench-scale flotation experiments using cationic collectors G-TAP and Flotigam V-4343 and using HF and H7SO4 as modifiers were employed to separate feldspar from quartz and to remove part of the titanium impurities. The best results were achieved with a combination of high-intensity wet magnetic separation and flotation. A feldspar concentrate containing 16.28% Al2O3, 10.75% K2O,2.84% Na2O, 69.97% SiO2 and 0.16% Fe2O3 was produced. A quartz concentrate containing 2.30% Al2O3, 0.48% K2O, 0.42% Na2O, 0.07% Fe2O3 and 96.20% SiO2 was also obtained

Grau de saponificação de óleos vegetais na flotação seletiva de apatita de minério carbonatítico

Ensaios de flotação, em bancada, de amostras de minério fosfático granulado e friável de Tapira-MG foram efetuados, testando-se diferentes graus de saponificação de três coletores aniônicos: "Hidrocol parcialmente hidrogenado", "Hidrocol sem hidrogenação" (obtidos a partir de soja) e ácido oléico. Os graus de saponificação usados foram de 40 %, 55 %, 70 %, 85 % e 100 %. Os ensaios foram feitos em pH 9,5. O óleo de babaçu, também cogitado como coletor, não permitiu grau de saponificação além de 40 %, mas serviu de controle da metodologia de quantificação do grau de saponificação. O Hidrocol parcialmente hidrogenado com grau de saponificação de 55 % foi o melhor, em termos de teor e recuperação de fósforo, relação CaO/P2O5 e teor de magnésia no concentrado, motivando testes de flotação em estágio de limpeza, sem e com a adição do coletor KE883B, um sulfosuccinato, também em pH 9,5, utilizando-se os óleos com grau de saponificação de 55 %. O Hidrocol parcialmente hidrogenado sem KE883B deu melhor resultado. Usou-se amido como depressor em todos os ensaios.

Effect of some process variables on flotability of sulfide nickel ores

The influence of grinding media, process water ions (calcium and thiosulfate) and pulp oxidation on flotability of sulfides nickel ores was investigated. Bench scale flotation experiments were carried out with Enonkoski ore using ethyl xanthate as collector. The results showed that the galvanic effect of mill iron controls the separation selectivity of pentlandite from pyrrhotite. Calcium and thiosulfate ions activated the flotation of sulfides with xanthate after using a steel mill for grinding. The ions improved also the selectivity of nickel separation. After grinding in ceramic mill, the ions depressed sulfide flotation but increased the selectivity of nickel flotation in the presence of a collector. Pulp oxidation improved both the flotability of sulfides and the selectivity of nickel flotation with both grinding methods.

Improved Pyrite Rejection by Chemically-Modified Fine Coal Flotation†

Abstract Improved pyrite rejection during fine coal flotation can be achieved by chemical pretreatment of the coal prior to flotation. The process involves conditioning the suspension with potassium monopersulfate or other peroxy compounds followed by conventional flotation. The ambient-temperature treatment seems to improve the hydrophobic character of certain low-rank coals as is evident from induction time measurements and bench-scale flotation experiments. In addition, the chemical pretreatment leads to an improvement in ash rejection and to enhanced depression of pyrite.

Thermal Treatment of Low-Rank Coal and Its Relationship to Flotation Response

Abstract The deleterious effect of oxidation processes on coal flotation is generally recognized by researchers in the field. The present study, however, demonstrates that properly controlled low-temperature heating can actually improve coal flotation and its separation from mineral matter especially for low-rank coals. With a lignite sample, low-temperature heating at 130°C for a given time under ambient atmosphere leads to a higher yield and greater ash rejection during subsequent bench-scale flotation experiments. By combining experimental results from Hallimond-tube and bench-scale flotation experiments, bubble attachment-time measurements, wetting phenomena, and FTIR spectroscopy, it is clear that thermal treatment under the above conditions, which involves dehydration and oxidation reactions, changes the coal sample to a more hydrophobic state. These new results provide further evidence of the complexities involved in the analysis of coal surface chemistry as related to flotation phenomena.