Effect of butanol on flotation separation of quartz from hematite with N-dodecyl ethylenediamine

In order to investigate the effect of butanol on quartz flotation when N-dodecyl ethylenediamine(ND)was used as collector, single mineral flotation and artificial mixed mineral(hematite and quartz were mixed at a mass ratio of 3:2) separation were conducted in the laboratory. Experimental results indicated that addition of butanol could improve the collecting performance of ND on quartz and enhance the floatability of quartz. Best flotation recovery of quartz was obtained when butanol was mixed with ND at a mass ratio of 1:1. Moreover, the molecular structure of alcohols had a significant effect on mineral recovery. Best separation efficiency could be obtained when tert-butanol was added as it had the largest cross-sectional area. Zeta potential measurements indicated that alcohols could strengthen electrostatic adsorption between quartz and collector. Molecular dynamic simulations revealed that co-adsorption of alcohols along with ND had taken place on the quartz surface, and ND/tert-butyl combinations were more easily absorbed on the quartz surface.     

Depression behaviors of N-thiourea-maleamic acid and its adsorption mechanism on galena in Mo-Pb flotation separation

In present study, a novel organic depressant N-thiourea-maleamic acid (TMA) was synthesized and applied as a galena depressant in the flotation separation of Mo-Pb ores. The depression behaviors of TMA were tested through flotation experiments. A wider separation window for single minerals over 90.0% was obtained at 30.0 mg/L TMA, confirming that TMA could depress galena significantly, while effected molybdenite floatability slightly. An effective separation was obtained for artificially mixed minerals and actual Mo-Pb ores. The adsorption mechanism on galena was revealed by UV–Vis spectra, zeta potential tests, Fourier transform infrared spectroscopy (FT-IR) analysis, contact angle tests and X-ray photoelectron spectroscopy (XPS) analysis. The zeta potentials of galena became more negative and the contact angle of galena dropped from initial 74.36° to 57.8° with 30.0 mg/L TMA depressant, inferring that TMA had adsorbed on galena surface. The analysis results of UV–Vis spectra, FT-IR and XPS gave further evidence that TMA might chemisorb on galena surface via Pb sites on galena surface and the thiourea group in TMA molecular structure, while the carboxyl group played a role of hydrophilicity.     

Flotation behavior of four dodecyl tertiary amines as collectors of diaspore and kaolinite

The flotation of diaspore and kaolinite by one of a series of tertiary amines (DRN, DEN, DPN and DBN) was investigated. The tertiary amines show better floating recovery for kaolinite compared to diaspore. The maximum recovery D-value is 45% over a pH range from 3 to 8. FT-IR spectra confirm the presence of hydroxyl groups on the surface of kaolinite and diaspore. Zeta potential measurements show that the mineral surfaces are negatively charged over a wide pH range. Ionization of hydroxyl groups mainly accounts for the surface charging mechanism. The adsorption of tertiary amines onto the mineral surface is due mainly to electrostatic effects and the difference in electrostatic effect between a collector and the two minerals can explain the flotation separation. Inductive electronic and steric effects from the substituent groups result in different collecting powers for the four tertiary amines.     

Adsorption behavior and mechanism of copper ions in the sulfidization flotation of malachite

Malachite is one of the main minerals used for the industrial enrichment and recovery of copper oxide resources, and copper ions are unavoidable metal ions in the flotation pulp. The microflotation, contact angle, and adsorption experiments indicated that pretreatment with an appropriate concentration of copper ions could improve the malachite recovery, and the addition of excess copper ions reduced the hydrophobicity of the malachite surface. The results of zeta potential tests indicated that sodium sulfide and butyl xanthate were also adsorbed on the surface of malachite pretreated with copper ions. X-ray photoelectron spectroscopy (XPS) results indicated that —Cu—O and —Cu—OH bonds were formed on the surface of the samples. After pretreatment with an appropriate concentration of copper ions, the number of —OH groups on the mineral surface decreased, whereas the number of Cu—S groups on the mineral surface increased, which was conducive to the sulfidization of malachite. After adding a high concentration of copper ions, the —OH groups on the mineral surface increased, whereas the number of Cu—S groups decreased, which had an adverse effect on the sulfidization flotation of malachite. Time-of-flight secondary ion mass spectrometry showed that pretreatment with copper ions resulted in a thicker sulfidization layer on the mineral surface.     

A nanoscale qualitative study on the role of sodium hydrosulfide in oxidized carrollite flotation

The surface species transformation of oxidized carrollite processing with NaHS and KBX was investigated. Flotation and contact angle tests indicate that the combination of NaHS and KBX takes a better flotation performance than adding NaHS or KBX alone. Thermodynamic analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) results confirm the stronger chemisorption of KBX occurs on the oxidized carrollite surface with NaHS, which is beneficial to remove the cobalt oxides, thus contributing to the superior floatability. Interestingly, less elemental sulfur was observed on the carrollite surface as the interaction of NaHS and KBX than adding NaHS alone. It suggests that elemental sulfur is not the main contributor to the restored floatability of oxidized carrollite through sulfidisation. This study provided a new perspective to correlate the surface species with xanthate adsorption and oxidized carrollite flotation through determining the various intermediate products.     

Exploration of amino trimethylene phosphonic acid to eliminate the adverse effect of seawater in molybdenite flotation

In this investigation, a chelating agent of amino trimethylene phosphonic acid (ATMP) was introduced to eliminate the adverse effect of seawater in molybdenite flotation. Microflotation results presented that high flotation recovery of molybdenite was achieved in freshwater using kerosene as the collector, but it was significantly decreased in the presence of seawater when pH > 9.5. Among the main ions in seawater, magnesium and calcium ions played a more detrimental role than others. After the addition of ATMP, molybdenite floatability can restore in seawater. Zeta potential distribution and solution chemistry calculation results illustrated that the decreased molybdenite floatability was attributed to the interaction of positive Mg(OH)_2(s) (major) and CaOH⁺ (minor) components with the molybdenite surface. The magnesium/calcium ions of positive components of Mg(OH)_2(s) and CaOH⁺ interacted with the ionized species of ATMP and then produced ATMP-calcium/magnesium complex, leading to the electrostatic repulsion between molybdenite and ATMP-calcium/magnesium complex that was restoring the molybdenite flotation. Hence, the ATMP can be utilized as an appropriate reagent to improve molybdenite flotation in seawater.     

Sulfidization regulation of cuprite by pre-oxidation using sodium hypochlorite as an oxidant

The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity. In this study, oxidant was used to modify cuprite surfaces to regulate the sulfidization of cuprite. Microflotation tests showed that the flotation recovery of pre-oxidized cuprite was nearly 25% higher than that of direct sulfidization flotation, which indicates that the cuprite surface activity was enhanced after pre-oxidation by Cu(I) species (weak affinity with sulfur ions) transformation to Cu(II) species (strong affinity with sulfur ions). Zeta potential, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry results showed that pre-oxidation improved cuprite sulfidization and promoted the formation of copper-sulfide species on the cuprite surfaces. The mineral surface stability and thus, xanthate species adsorption on the cuprite surfaces were improved. The surface-adsorption measurements and infrared spectroscopy showed that a large amount of xanthate species was adsorbed onto the sulfidized cuprite surfaces after pre-oxidation, which enhanced the cuprite hydrophobicity and improved the cuprite flotation.     

利用磷灰石实现硫化矿浮选废水回用的试验评价

出于环境的考虑,越来越多的选矿厂均利用回水以减轻废水对环境的冲击和对水资源的依赖.工业生产经验表明,回水使用量的增加会对浮选带来不利的影响,尤其是对复杂矿化矿的优先浮选.浮选选择性降低的主要原因是溶液中重金属离子对闪锌矿或黄铁矿的意外活化.本文应用微型浮选试验,吸附试验和表面测试研究了利用磷灰石来实现硫化矿浮选废水回用的可行性.试验表明,磷灰石可增强对闪锌矿的抑制而提高浮选的选择性.微型浮选和表面测试表明,磷灰石与闪锌矿竞争吸附溶液中的重金属, 从而降低闪锌矿表面的重金属浓度.     

Influences of collector DLZ on chalcopyrite and pyrite flotation

The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments, zeta potential measurements and infrared spectrum analysis. Flotation test results indicate that DLZ is the selective collector of chalcopyrite. Especially, the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems, while the recovery of pyrite is less than 10%. When using CaO as pH regulator, at pH=7-11, the floatability of pyrite is depressed and the recovery is less than 5%. Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ, confirming that collector DLZ shows selectivity to chalcopyrite and pyrite. And FT1R results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.     

An in situ ATR-FTIR study of mixed collectors BHA/DDA adsorption in ilmenite-titanaugite flotation system

This paper researched the enhanced flotation separation performance of ilmenite and titanaugite using the mixed collector benzhydroxamic acid/dodecylamine(BHA/DDA). The interface assembly mechanism was mainly investigated through in situ attenuated total reflectance Fourier transform infrared(ATRFTIR) spectroscopy combined with the two-dimensional correlation spectroscopy(2 D-COS) and X-ray photoelectron spectroscopy(XPS). It has been found that BHA/DDA mixed collectors successfully separate ilmenite from titanaugite at a molar ratio of 8:1. Zeta potential experiments suggested that, in the presence of mixed collector system, the BHA-DDA complex adsorbed on the ilmenite surface via the chemically adsorbed BHA and the electrostatically adsorbed DDA, however, the complex adsorbed on the surface of titanaugite unstably. According to in situ ATR-FTIR combined with 2 D-COS and XPS results,the interface assembly mechanism of BHA/DDA is summarized as: the function group of BHA molecules first binds to the metal sites on minerals to form bidentate ligand, then DDA co-adsorbed with BHA on the surface of minerals through hydrogen bonding. DDA may change the adsorption modes of some BHA on the ilmenite surface from four-membered ring to five-membered ring, while the modes on the titanaugite surface is true opposite. Finally, recommended adsorption configurations of the BHA/DDA complex on the two mineral surfaces are proposed.     

利用磷灰石实现硫化矿浮选废水回用的试验评价

出于环境的考虑，越来越多的选矿厂均利用回水以减轻废水对环境的冲击和对水资源的依赖．工业生产经验表明，回水使用量的增加会对浮选带来不利的影响，尤其是对复杂矿化矿的优先浮选．浮选选择性降低的主要原因是溶液中重金属离子对闪锌矿或黄铁矿的意外活化．本文应用微型浮选试验，吸附试验和表面测试研究了利用磷灰石来实现硫化矿浮选废水回用的可行性．试验表明，磷灰石可增强对闪锌矿的抑制而提高浮选的选择性．微型浮选和表面测试表明，磷灰石与闪锌矿竞争吸附溶液中的重金属，从而降低闪锌矿表面的重金属浓度．     

Theoretical study of 2-mercaptobenzimidazole derivatives as chelating collectors in flotation separation of galena and pyrite

Three 2-mercaptobenzimidazole derivatives, 1-ethyl-2-mercapto-benzimidazole (EMBI), 1-propyl-2-mercapto-benzimidazole (PMBI) and 1-benze-2-mercapto-benzimidazole (BMBI), were designed and synthesized in the paper, and their collecting behavior in flotation separation process of galena over pyrite was investigated by flotation tests on lab scale. Apart from this, density functional theory (DFT) calculation and molecular dynamics (MD) simulation were also used to elucidate their collecting mechanism. Results of flotation tests indicate that separation of galena over pyrite is feasible at pH 10, and BMBI has the best floatability among three collectors. DFT calculations show that BMBI has the highest occupied molecular orbital (HOMO) energy and strongest collecting efficiency. The adsorption mode of three collectors on mineral surface by MD method indicates that the combination processes of collectors with mineral are exothermic, and the higher the binding energy, the firmer the collector adsorbs on the mineral surface and the higher collecting capacity. The calculation results demonstrate that the floatability of three collectors follows the order: BMBI > PMBI > EMBI, which is highly consistent with the flotation tests.     

芳烃捕收剂的结构对浮选性能的影响

通过测定煤泥与药剂作用前后的Zeta电位、接触角、气-液表面张力以及红外光谱,研究了单取代苯、双取代苯和双取代萘3类芳烃捕收剂的结构对浮选活性的影响,探讨了煤与芳烃捕收剂的吸附作用机理.结果表明:3类芳烃捕收剂浮选活性大小依次为:双取代萘>双取代苯>单取代苯;当芳烃捕收剂的苯环个数相等时,其浮选活性的差异主要取决于最长取代基的碳原子个数,其它取代基起辅助作用,而且取代基越多浮选活性越强;当最长取代基碳原子个数为5时,其浮选效果最佳;芳烃捕收剂与煤中的烷基、胺基和醚键作用属于化学吸附.     

胶磷矿浮选技术的改进

胶磷矿浮选过程选择性差的根本原因,是由于矿物组分尤其镁离子的溶解,造成矿物表面性质相互转化和捕收剂皂盐在矿物表面无选择性沉积. 通过控制浮选条件和药剂制度,尽可能避免捕收剂和溶解组份在矿物表面无选择性吸附或沉积,是选择性调控胶磷矿浮选性质的重要手段. 此外,采用机柱联合浮选装置来改善胶磷矿的浮选分离环境,对提高其浮选效率也非常重要. 实验表明:对原矿含五氧化二磷22.16%、氧化镁3.15%、二氧化硅25.41%的湖北远安磷矿石,通过采取以上改进措施,采用简单的单一浮选工艺,可获得磷精矿五氧化二磷品位＞30%、回收率＞80%和氧化镁品位1%左右的分选指标     

Adhesion forces for water/oil droplet and bubble on coking coal surfaces with different roughness

Surface roughness plays a significant role in floatability of coal. In the present paper, coking coal surface was polished by three different sandpapers and the surface properties were characterized by contact angle and roughness measurements. The effect of surface roughness on floatability was investigated by adhesion force measurement system for measuring interaction forces between droplets/bubbles and coking coal surfaces with different roughness. The results showed that the contact angle decreased with increasing roughness yet the adhesion force between the water droplet and coal surface increased owing to the increased contact line and the appearance of line pinning. Maximum adhesion forces between water and surfaces were 111.70, 125.48, and 136.42 μN when the roughness was 0.23, 0.98, and 2.79 μm, respectively. In contrast, under a liquid environment, the adhesion forces between air bubble/oil droplet and coal surfaces were decreased with increasing roughness because of the restriction by water. Maximum adhesion forces of increasing roughness were 97.14, 42.76, and 17.86 μN measured at interfaces between air bubble and coal surfaces and 169.48, 145.84, and 121.02 μN between oil droplet and surfaces, respectively. Decreasing roughness could be beneficial to the spreading of oil droplets and the adhesion of bubbles which is conducive to flotation separation.     

Insights into the floatability between spodumene and albite from crystal chemistry standpoint

Spodumene is a silicate mineral rich in lithium. However, the gangue mineral, albite has similar crystal chemical structure and composition to spodumene. In this work, the density functional theory (DFT) calculation was taken to research the floatability from the perspective of crystal chemistry. And contact angle test and reagent adsorption test were used to support the simulation results. In addition, the weighted total density of broken bonds is proposed for the first time to judge the generation probability of cleavage surface. The DFT calculation results display that the Na and Al sites on the albite surface are the adsorption sites of water molecules. While the water molecules only bond with Al atom on the surface of spodumene and each Al site can adsorb only one water molecule. Thus, the wetting effect of water molecules on the albite surface is stronger than that of spodumene. This is consistent with the result of contact angle. In sodium oleate system, the oleic acid anion is adsorbed on the spodumene surface in form of a multicomponent ring while the albite is a single ring. Theoretically, oleic acid anion can be strongly adsorbed on the surface of spodumene and albite under vacuum. The adsorption strength of spodumene is higher than that of albite. However, on hydrated surface, the adsorption strength of oleic acid anion on mineral surface is greatly reduced due to the interaction between water molecules and metal site on mineral surface. Thus, spodumene and albite are hard to float without external activated ions in sodium oleate system.     

Effect of depressants on flotation separation of magnesite from dolomite and calcite

The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing. This work studied the inhibition effects of carboxymethyl cellulose (CMC), sodium lignosulphonate, polyaspartic acid (PASP) and sodium silicate on flotation behaviors of magnesite, dolomite and calcite, providing guidance for the development of reagents in magnesite flotation. The micro-flotation results showed that among these four depressants, sodium silicate presented the strongest selectivity due to the highest recovery difference, and the flotation separation of magnesite from dolomite and calcite could be achieved by using sodium silicate as the depressant. Contact angle measurement indicated that the addition of sodium silicate caused the largest differences in surface wettability of the three minerals, which was in line with micro-flotation tests. Furthermore, zeta potential test, the Fourier transform infrared (FT-IR) spectroscopy and atomic force microscope (AFM) imaging were used to reveal the inhibition mechanism of sodium silicate. The results indicated that the dominated component SiO(OH)₃^? of sodium silicate could adsorb on minerals surfaces, and the adsorption of sodium silicate hardly affected the adsorption of NaOL on magnesite surface, but caused the reduction of NaOL adsorption on dolomite and calcite surfaces, thereby increasing the flotation selectivity.     

脂类捕收剂DLZ对黄铜矿和黄铁矿浮选的选择性作用

通过浮选实验、吸附量和红外光谱测定,考察了捕收剂DLZ对黄铜矿和黄铁矿浮选性能的影响及作用机理.结果表明:DLZ在pH=2.7～12.05时对黄铜矿的捕收能力强,最大回收率95.7%,而对黄铁矿的捕收能力弱,且PH=6.9～12.05时其回收率小于10%.用CaO作pH调整剂时,在pH=7～11时黄铜矿的回收率与用NaOH调PH相差不大,但黄铁矿可浮性被抑制,回收率低于5%.DLZ在黄铜矿上的吸附量比在黄铁矿上的大,特别是强碱条件下;其吸附量随用量的增加而增大.DLZ与矿物作用的红外光谱分析表明:黄铜矿与DLZ作用后出现了DLZ的相关特征吸收峰,而黄铁矿与DLZ以及Cu~(2+)作用前后的红外光谱曲线基本没有变化,可见DLZ在黄铜矿表面的吸附属于化学吸附,在黄铁矿表面的吸附属于物理吸附.     

Growth of covellite crystal onto azurite surface during sulfurization and its response to flotation behavior

In this work, the growth of copper sulfide crystal onto azurite surfaces during sulfurization and its response to flotation are investigated. Filed emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM) and X-ray diffraction (XRD) studies confirmed that the sulfurization of azurite is not limited to the mineral surface, but rather penetrates into the bulk to form covellite crystal (syn-CuS), creating favorable conditions for the stable adsorption of xanthate and greatly promoting the azurite flotation. Additionally, as demonstrated by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS) analyses, a redox reaction occurred during this process, and Cu(Ⅱ) onto the mineral surface was reduced to Cu(I). Correspondingly, reduced S^2- was oxidized to (S₂)^2-, (S_n)^2-, and even to deeper oxidation state S⁰, (S_xO_y)^n- and SO₄^2-. Excess sodium sulfide strengthens copper sulfide to form onto the azurite surface, and provides enough raw material for crystal copper sulfide to grow, resulting in the formation of “flake-like” covellite with a better crystallinity. However, the floatability of azurite decreased dramatically under this condition, because the generated massive colloidal copper sulfide in flotation pulp deteriorates the flotation environment, resulting in a decreased effective adsorption of collector onto azurite surfaces.