Hydroxamic Acid Collector Research Articles

Separation of cerussite and calcite by flotation using tert-butylbenzylhydroxamic acid collector and insights to its adsorption mechanism

In this study, a modified hydroxamic acid collector, tert-butylbenzylhydroxamic acid (TBHA), was used as a collector and applied to the flotation separation of cerussite and calcite. The results of single-mineral flotation experiments showed that TBHA had excellent collecting effect on cerussite, and when acidified water glass (AWG) was used as the depressant, TBHA could realize the efficient flotation separation of cerussite and calcite. The adsorption mechanism of TBHA was investigated by adsorption amount, Zeta potential, FTIR and X-ray photoelectron spectroscopy (XPS) measurements. The results of adsorption amount showed that TBHA adsorbed more on cerussite under the same conditions; the results of Zeta potential, FTIR and XPS showed that TBHA could be selectively adsorbed on the surface of cerussite in the presence of AWG. In summary, TBHA was adsorbed on the surface of cerussite by chemisorption, which enhanced the hydrophobicity of the cerussite surface. Therefore, TBHA has great potential in the flotation of cerussite.

5-Dodecylsalicylaldoxime as a Novel Collector in Cassiterite Flotation: Performance and Mechanism

Hydroxamic acid and fatty acid collectors are commonly used in cassiterite flotation but face issues like poor selectivity, high dosage, and strict requirements on ore composition and grinding fineness. This study investigates the collecting performance of a novel flotation reagent, 5-dodecylsalicylaldoxime (DSA), in cassiterite flotation. DSA exhibits remarkable selectivity, achieving an impressive 82.5% recovery of Sn at a concentration of only 9 × 10−5 mol/L in single mineral flotation tests. Moreover, DSA significantly outperforms benzohydroxamic acid (BHA), enhancing Sn recovery by 33.55% in artificially mixed ore flotation experiments. In the flotation test of a copper–tin polymetallic ore, compared with the BHA flotation effect, the recovery rate of DSA increased by 12.29% when the Sn grade remained basically unchanged. Analyses such as zeta potential, FT-IR, and XPS indicate that DSA’s superior collecting performance stems from its stable adsorption onto cassiterite surfaces through a chelating ring formation, resembling the adsorption mechanism of hydroxamic acid collectors. Furthermore, DSA’s larger cluster size in the solution compared to BHA contributes to its enhanced selectivity and collectability. Overall, DSA emerges as a promising alternative to traditional cassiterite flotation collectors, offering a combination of enhanced selectivity, lower dosage requirements, and robustness in complex ore systems.

Selective Separation Behavior and Study on the Interaction Mechanism of 2-Hydroxy-3-Naphthylmethyl Hydroxamic Acid and Cassiterite

In this study, the performance of 2-hydroxy-3-naphthylmethyl hydroxamic acid (NHA) in cassiterite flotation was investigated. The aim was to understand the mechanism of action of NHA for the first time. The effect of NHA as a collector in the flotation separation of cassiterite, calcite, and quartz was investigated via microbubble flotation experiments. The experimental results showed that the maximum recovery of cassiterite in the presence of NHA was 91.76%. This was attributed to the selective adsorption of NHA on the cassiterite surface. NHA showed a stronger collection performance for cassiterite than calcite and quartz. Therefore, the mechanism of NHA-cassiterite interaction was investigated using zeta potential, the logarithmic solubility plot (LSD), Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscope (SEM) analyses. This study introduces a new adsorption process and mechanism for the NHA-based adsorption of cassiterite. The results show that, under neutral conditions, the solute components of cassiterite surface lattice ions mainly exist in the form of Sn–OH complexes. Chemisorption occurs between cassiterite and NHA which is adsorbed onto the cassiterite surfaces through interaction with O sites, rather than Sn sites as is traditionally expected. Further, the hydroxyl and hydroxyl groups of NHA are chemically coordinated with Sn–OH on the surface of cassiterite to form a six-membered chelate ring. This proposed mechanism can be extended to most systems in which metal ions interact with hydroxamic acids bearing hydroxyl groups. This contributes to a better understanding of the activation mechanism of hydroxamic acid collectors in cassiterite flotation.

Flotation Performance and Adsorption Mechanism of Cerussite with Phenylpropenyl Hydroxamic Acid Collector

In this paper, the flotation separation of cerussite and quartz under different experimental conditions was studied by using phenylpropenyl hydroxamic acid (PHA) as a collector. The flotation performance of PHA was studied through experiments involving pure minerals and artificial mixed minerals, and the results showed that PHA has good selectivity and collecting ability for cerussite. The adsorption mechanism of the collector on the surface of cerussite was investigated via adsorption capacity experiments, zeta potential tests, FTIR spectroscopy, and XPS analysis. The adsorption capacity results showed that PHA can be well adsorbed on the surface of cerussite. The results of the zeta potential tests showed that PHA has strong chemical adsorption on the cerussite surface. FTIR and XPS analysis showed that PHA may form a Pb–PHA complex on the cerussite surface to improve the floatability of cerussite.

Synthesis and utilization of a novel oleate hydroxamic acid collector for the flotation separation of bastnaesite from barite

Hydroxamic acid collectors display excellent selectivity but poor collecting ability in bastnaesite flotation. Improving the collecting capacity of hydroxamic acid collector appropriately become an effective method to enhance the performance of flotation reagents. A novel oleate hydroxamic acid (OLHA) as a collector was synthesized and applied to bastnaesite flotation in this work. The structure of OLHA was characterized by Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The single mineral and artificial mixed minerals flotation experiments results show that OLHA achieved efficient flotation separation of bastnaesite and barite when odium hexametaphosphate (SHMP) was used as depressant. The contact angle, zeta potential, FTIR and X-ray Photoelectron Spectroscopy (XPS) measurements were performed to investigate the adsorption mechanism of OLHA. The contact angle results show that OLHA significantly improved the surface hydrophobicity of bastnaesite. Zeta potential and FTIR results show that in the presence of SHMP, OLHA selectively adsorbs to the surface of bastnaesite. Over all, OLHA adsorbs on the surface of bastnaesite through chemically adsorption, and strengthen the hydrophobicity of bastnaesite surface. Therefore, OLHA is a promising collector for bastnaesite flotation.

Investigation on flotation separation of bastnaesite from calcite with a novel collector: Octylamino-bis-(isobutanohydroxamic acid)

Bastnaesite is an important mineral resource, usually associated with calcite and other minerals, flotation is one of the most widely used methods in the selection process. Collector is the key to achieve flotation separation of bastnaesite from gangue mineral. The effect of a new hydroxamic acid collector with two functional groups: Octylamino-bis-(isobutanohydroxamic acid) (OIBHA), on the flotation separation of bastnaesite from calcite was investigated. The Single mineral and artificial mixed ore flotation results revealed that OIBHA exhibited better collecting ability and selectivity compared with the conventional hydroxamic acid collector octanohydroxamic acid (OHA). Effective separation between bastnaesite and calcite can be realized. The concentrate with 68.82 % REO grade and 90.23 % REO recovery was obtained with 3 × 10−4 mol/L OIBHA. Fourier transform infrared (FTIR) analysis, zeta potential measurements and quantum chemical calculations were used to investigate the selective adsorption mechanism of OIBHA. The results of FTIR analysis and zeta potential measurements showed that OIBHA was strongly adsorbed on the surface of bastnaesite, but did not interact with calcite. Quantum chemical calculations results indicated OIBHA matched well with bastnaesite surface, thereby improved the selectivity. The results in this paper are instructive for the study of the spatial matching properties of collectors and mineral surfaces.

Flotation Behavior and Adsorption Mechanism of Phenylpropyl Hydroxamic Acid As Collector Agent in Separation of Fluorite from Calcite.

The hydroxylamine method involves the synthesis of a new hydroxamic acid collector, i.e., phenylpropyl hydroxamic acid (PHA), from methyl cinnamic hydroxamic acid. Flotation test results show that PHA exhibits good selective collection ability. The adsorption mechanism of PHA is investigated using the zeta potential, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that PHA formed a new Ca-O bond with Ca2+ on the fluorite surface via chemical adsorption. A new five-element chelated hydroxamate group may have formed in Ca on the fluorite surface. The PHA selectivity is fully explained via density functional theory (DFT) calculations, and an adsorption model is established.

Preparation of cinnamic hydroxamic acid collector and study on flotation characteristics and mechanism of scheelite

In this paper, using methyl cinnamate as raw material, the new cinnamic hydroxamic acid collector (CIHA) was synthesized by the hydroxylamine method. The collector performance of hydroxamic acid was investigated for scheelite and gangue calcite, and the flotation separation test of scheelite and calcite was carried out with CIHA as the collector. The interaction mechanism between hydroxamic acid and scheelite minerals has also been investigated through zeta potential, Fourier transform infrared spectroscopy (FTIR) experiments, X-ray photoelectron spectroscopy (XPS) experiments, and density functional theory (DFT) calculation. The single mineral flotation test and artificially mixed ore showed that CIHA had an excellent collection effect and selectivity. Zeta potential, FTIR, and XPS showed that CIHA was adsorbed on the scheelite surface by strong chemical adsorption. The active group of CIHA was analyzed through quantum chemical calculation. It was speculated that CO and NO bonds could synthesize a five-membered chelated hydroxamic acid group with Ca element chelate on scheelite surface, changing hydrophobicity and making it more likely to emerge from the pulp.

Synthesis of sodium oleate hydroxamate and its application as a novel flotation collector on the ilmenite-forsterite separation

Collectors are important for mineral flotation. In this work, a novel hydroxamic acid collector, i.e. sodium oleate hydroxamate (NaOLH), was synthesised and applied for ilmenite flotation. The collector was designed by constructing an oleic acid chain and hydroxamic acid group into the collector’s molecular structure, based on the flotation mechanism of ilmenite. Liquid chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy were employed to identify the component and structure of NaOLH. Micro-flotation was performed to explore the flotation performance of NaOLH. The absorption mechanism was investigated by zeta potential, Fourier transforms infrared spectroscopy, and X-ray photoelectron spectroscopy. Results demonstrated that NaOLH had a stronger flotation performance than the conventional collector sodium oleate (NaOL). The NaOLH was adsorbed onto the surface of the ilmenite and forsterite, and the O and N atoms of NaOLH were mainly chemisorbed on ilmenite via Fe and Ti sites on the surface, whereas mainly reacted with Mg sites on the forsterite surface. The distribution of NaOLH and NaOL at the solid–liquid interface was studied by molecular dynamics simulation. Results showed that the adsorption capacity between NaOLH and ilmenite was stronger than that of NaOL. Taken together, results suggest that the NaOLH is a potentially novel and a promising collector for ilmenite flotation.

De-sliming followed by froth flotation for the recovery of phosphorus and enrichment of rare earth elements from Florida waste clay

Reprocessing and valorization of secondary resources is a possible solution to alleviate the supply-demand disparity for critical materials. The current study investigated the recovery of P and enrichment of REEs from Florida waste clay (WC). Clays, dolomite, and quartz are the main associated gangue minerals, while apatite is the predominant P-bearing mineral, and monazite and xenotime are the rare earth minerals in this WC. A 1.5-in. diam. hydro-cyclone unit was initially employed for the removal of clays. Froth flotation was then examined for the separation of values from the cyclone underflow. Various depressants and surface modifying agents were assessed for both direct and reverse flotation separations. Results showed that the direct flotation does not offer a solution for the selective recovery of P from WC. Despite their documented affinity for apatite and rare earths, hydroxamic acid collectors do not produce a selective separation. A single-stage reverse cationic process provides a more economically viable route due to its capability to avoid the loss of REEs. Test results of the single-stage reverse cationic process indicated that the P2O5 grade was increased to 21 wt.% from an initial grade of ∼8 wt.% with a corresponding recovery of approximately 80%. The REE content was elevated from an initial value of 307.1 ppm to 800 ppm, with an 80% recovery resulting from the same process. The removal of clays, silicates, and carbonates up to a point to meet the medium-grade phosphate ore specifications also facilitates the subsequent recovery of REEs using chemical separation.

Structural modification of hydroxamic acid collectors to enhance the flotation performance of malachite and associated mechanism

A series of N-hydroxy-N-aryl amide collectors, including N-hydroxy-N-benzyl acetamide (NHNBA), N-hydroxy-N-benzyl butyramide (NHNBB), N-hydroxy-N-phenyl acetamide (NHNPA) and N-hydroxy-N-phenyl butyramide (NHNPB), was designed in this study and employed for the first time in malachite flotation. Flotation tests conducted in the absence of frothers and activators revealed that the N-hydroxy-N-aryl amide collectors realized effective separation of malachite from calcite and quartz, which could not be readily achieved with benzohydroxamic acid (BHA). NHNBB exhibited optimal collection ability and selectivity for malachite over calcite and quartz. Quantum chemistry calculations, solution chemistry analysis and FTIR spectroscopy and XPS analyses revealed that in addition to electrostatic attraction, NHNBB possibly interacted with the malachite surface via chemisorption by forming five-membered-ring complexes, resulting in an efficient collection capacity for malachite.

Effect of Al3+ and Mg2+ on the flotation of fluorapatite using fatty- and hydroxamic-acid collectors – A multiscale investigation

Fluorapatite flotation is influenced by the dissolved lattice metal ions. Al3+ and Mg2+ from the associating gangue minerals influence the adsorption of collector molecules onto the fluorapatite surface during flotation. Hence, unveiling new insights on such interactions in the context of froth flotation at an atomic level paves the way for improving flotation selectivity. An original multiscale approach has been developed involving flotation experiments, electro-kinetic and adsorption density measurements, X-ray photoelectron spectroscopy studies, and density functional theory simulations. Fatty acid establishes an enhanced interaction with the bare apatite surface compared to the hydroxamates. Na+ counter-ion contributes to the adsorption of fatty acid on bare apatite. Both Al3+ and Mg2+ ions are beneficial for the adsorption of fatty acid, thereby the fluorapatite flotation. For octanohydroxamic acid, the presence of Al3+ results in a stronger collector-apatite interaction, and therefore an enhanced flotation. For fatty acid and hydroxamates, adsorption of Mg2+ leads to an improved collector-apatite interaction. Benzohydroxamic acid is more vigorously adsorbed than octanohydroxamic acid in the presence of Mg2+. Fatty acid establishes a stronger interaction with bare and Al3+/Mg2+-treated fluorapatite, as opposed to hydroxamates. Mg2+ is more favorable than Al3+ in fluorapatite flotation using both fatty acid and hydroxamates.

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.

Mechanism of recovery processes for rare earth and iron from Bayan Obo tailings

Abstract Rare earth (RE) and iron minerals in tailings exhibit fine embedded granularity and are closely associated with silicates, carbonates, and other lode minerals, which are difficult to be recycled. Studies of these tailings led to some new processes of ore dressing, involving grinding, RE flotation, strong magnetic separation, and positive iron flotation. In this closed circuit process, RE and iron minerals were separated after grinding, and the materials resulted from the flotation of small-sized RE and iron mineral particles were accurately controlled using a combination of inhibitors, dispersants, pH regulators, and collector agents. The ore dressing were ground to a fineness of 0.045 mm, which was a process accounting for 95.6% of the material. The amount of water glass, NXJ (a combination of sodium carbonate mixed with a fine mud dispersant), and BGH (hydroxamic acid collector, a combination of 3-carboxy-2-naphthylhydroxamic acid and C5-9 hydroxamic acid) used in the primary separation of RE were 2.4 kg/t, 2.5 kg/t, and 2.4 kg/t, respectively. The dosages of ammonium fluorosilicate and GXY (fatty acid collector, a combination of sodium oleate mixed with oxidized paraffin soap) used with iron coarse were 2.2 kg/t and 1.2 kg/t, respectively. The RE collectors achieved chemical separation of Ce, La, and other particles and formed stable five-membered cyclic chelates. Consequently, through the closed circuit experiment, the RE grade and recovery rate in the RE concentrate were improved to 50.3 and 61.6%, respectively. The total iron (TFe) grade and recovery rate in the TFe concentrate were improved to 64.0 and 30.0%, respectively, and other useful metals were also enriched; this process managed secondary recycling of RE and TFe possible, leading to improvements in resource utilization.

Preparation of a novel bis hydroxamic collector and its impact on bastnaesite flotation

A novel hydroxamic acid collector, Octylamino-bis-(isobutanohydroxamic acid) (OIBHA), for bastnaesite flotation was designed by constructing a double branched hydroxamic acid molecular structure and synthesized in the laboratory. Micro-flotation experiments were carried out to study the flotation performance of OIBHA. The adsorption mechanism was investigated by zeta potential, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Micro-flotation experiments revealed that OIBHA exhibited good collective and selective ability, and the effective separation between bastnaesite and fluorite can be realized. FTIR, zeta potential and XPS analysis results indicated that OIBHA was chemically adsorbed on the Ce site of bastnaesite surface. The introduction of the secondary hydroxamic acid group to form the branched molecular structure can improve the collecting ability and selectivity simultaneously.

Flotation separation of bastnaesite from calcite using novel octylmalon dihydroxamic acid as collector

A novel hydroxamic acid collector, octylmalon dihydroxamic acid (OMHA), was designed by introducing the secondary hydroxamic group into octanohydroxamic acid (OHA) and synthesized. OMHA was originally used as the collector in the flotation separation of bastnaesite from calcite. The flotation results revealed that OMHA exhibited better collecting ability and selectivity compared with the conventional hydroxamic acid collector OHA. Effective separation between bastnaesite and calcite can be realized. The concentrate with 69.26% REO grade and 89.49% REO recovery was obtained with 3 × 10−4 mol/L OMHA under natural slurry pH. Zeta potential measurements and FTIR spectra analysis indicated that OMHA was strongly adsorbed on bastnaesite surface but did not interact with calcite. XPS results demonstrated that OMHA was chemically adsorbed on the Ce site of bastnaesite surface. The introduction of the secondary hydroxamic group significantly improved the flotation performance, especially in selectivity.

A novel decanedioic hydroxamic acid collector for the flotation separation of bastnäsite from calcite

In this work, decanedioic hydroxamic acid (DDHA) was introduced as a novel collector for the flotation separation of bastnӓsite and calcite, and the results were compared with those obtained for the conventional hydroxamic acid collectors benzohydroxamic acid (BHA) and octyl hydroxamic acid (OHA). The microflotation results showed that DDHA had better selectivity than BHA and OHA for the flotation of bastnӓsite from calcite. The flotation of artificially mixed minerals confirmed that the effective separation of bastnӓsite from calcite could be realized in the presence of DDHA. The zeta potentials of mineral surfaces with or without these collectors were measured, and the results indicated that DDHA strongly interacted with the bastnӓsite surface but was not adsorbed on the calcite surface.

Beneficial effects and mechanism of lead ions for bastnaesite flotation with octyl hydroxamic acid collector

The beneficial effects and mechanism of Pb ions (Pb2+) for bastnaesite flotation were systematically investigated. The results of micro-flotation tests indicated that the Pb2+ effectively enhanced the floatability of bastnaesite with octyl hydroxamic acid (OHA) collector. Maximum recovery of 67% was obtained at pH 8–9. Adsorption of the hydrolyzing species of Pb occurred at this pH, which provided more active sites on the bastnaesite surface for OHA absorption. Furthermore, lead species interacted with active Ce sites to form lead-containing complexes (Ce-O-Pb) on the bastnaesite surface, and the hydrophobic Pb-OHA chelates were formed via chemical adsorption between Pb2+-activated bastnaesite and OHA. These findings were confirmed by adsorption measurements, zeta-potential measurements, Fourier transform infrared analysis (FT-IR), and X-ray photoelectron spectroscopy (XPS).

A Micro-Scale Investigation of the Adsorption of Collectors on Bastnaesite

A micro-scale investigation was carried out by applying atomic force microscopy (AFM) to study in situ the adsorption of various collectors, i.e., oleic acid, octanohydroxamic acid (HA), and salicylhydroxamic acid (SHA), on bastnaesite in aqueous solutions. The obtained AFM images show that the surface morphology of bastnaesite changes greatly after it comes into contact with the solutions of the collectors, suggesting that all these collectors can effectively adsorb onto bastnaesite. Increasing temperature can facilitate the adsorption of oleic acid onto bastnaesite. Results from attenuated total reflectance–Fourier transform infrared spectrometry (ATR-FTIR) also show that all of these collectors adsorb strongly onto bastnaesite, with strong absorbance spectra being detected. The ATR-FTIR results confirm those obtained by AFM. In general, hydroxamic acid collectors (HA and SHA) adsorb onto bastnaesite mainly in the form of insoluble metal hydroxamate. This specific adsorption mechanism explains that a high selectivity with a moderate collectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite.

Selective Flotation of Copper Oxide Minerals with A Novel Amino-Triazole-Thione Surfactant: A Comparison to Hydroxamic Acid Collector

ABSTRACT Developing specific flotation collectors to improve the separation and enrichment of copper oxide minerals from their ores is still a challenging job. In this article, a novel chelating collector, 5-(2,4,4-trimethylpentyl)-4-amino-1,2,4-triazolidine-3-thione (TMATT), was designed to separate and recover copper oxide minerals, and its flotation response to malachite, calcite, and quartz was compared with that of the traditional collector n-octyl hydroxamic acid (OHA). The findings of contact angle and micro-flotation indicated that TMATT exhibited stronger hydrophobization and better flotation performances to malachite than OHA, and also held the high flotation selectivity against quartz and calcite. The bench-scale flotation outcomes showed that TMATT achieved the high-efficient flotation separation and enrichment of copper oxide minerals from the mixed sulfide-oxide copper ore. XPS, FTIR, AFM, and zeta potential deduced that the adsorption of malachite toward TMATT was related to the reduction of surface Cu(Ⅱ) to Cu(Ⅰ) and the formation of TMATT-Cu(Ⅰ) surface complexes in which the exocyclic N and S atoms of TMATT bonded with the surface Cu(Ⅰ) on malachite. The superior hydrophobicity of TMATT-Cu(I) surface complexes in comparison to that of OHA-Cu(Ⅱ) surface complexes, the favorable five-membered ring bonding mode on malachite surfaces and the preferable chelating selectivity to soft acid Cu(Ⅰ) rather than to hard acid Ca(Ⅱ), deserved TMATT to possess better flotation response to malachite against calcite than OHA.