Electrochemical flotation of diethyldithiocarbamate-pyrrhotite system

Using sodium diethyldithiocarbamate as a collector the flotation behavior of pyrrhotite was investigated.The relationship between potential and pH range for pyrrhotite flotation was established. The results show that the flotation of pyrrhotite is dependent on pulp potential at certain pH values. Pyrrhotite has good floatability from pH 2 to pH 12, and poor flotability at pH＞12. Cyclic voltammetry and Fourier transform infrared spectrum analysis show that the major adsorption product of DDTC on pyrrhotite is tetraethylthiuram disulfide. The intensity of Fourier transform infrared signals of tetraethylthiuram disulfide adsorbed on pyrrhotite and the anode current of a pyrrhotite electrode and flotation response of pyrrhotite are correlated with pulp potentials.     

Froth flotation of scheelite – A review

Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation of scheelite from other calcium-bearing minerals, in particular calcite, fluorite and apatite. Due to similar properties, most attempts have limited success or only specific application(linked to a type of ore or a location). This article aims at reviewing all general physical-chemical information on froth flotation of scheelite, including electrokinetic properties, influence of p H and already existing reagents as well as ones still under examination. It appears that chelating or mixed collectors and modified versions of sodium silicate and quebracho hold great promise for scheelite flotation, while the use of said depressants and/or promoters seems inevitable.     

Mechanism of separating pyrite and dolomite by flotation

To study the mechanism of separating pyrite and dolomite by flotation, the acting mechanisms of WHL depressor and both the minerals were studied by means of thermogravimetric and differential thermal analysis （TG-DTA）, Fourier transform infrareddiffuse reflection spectroscopy （PTIR-DRS）, and X-ray photoelectron spectroscopy （XPS）. The results indicated that WHL formed metal salts with metal ions dissolved in water from dolomite and pyrite, which then deposited on their surfaces. Both of the minerals could be depressed by WHL. In the process of flotation, sulfur was created besides the WIlL being absorbed on the surface of the sulfur concentrate, and its recovery rate was slightly affected.     

A novel collector RL for flotation of bauxite

The flotation properties of single minerals such as diaspore, kaolinite and pyrophllite in bauxites were investigated using RL as collector. The effects of regulators and unavoidable ions on flotation were studied. Based on the results of single minerals flotation, the separation experiments of mixed minerals and bauxite ore were carried out. The results of closed circuit test on the ore show that, using RL as collector, Na2CO3 and (NaPO3)6 as modifiers, the grade of Al2O3 and SiO2 are respectively 70.74% and 6.37% in concentrate(Al/Si 11.11 ), and the recovery of Al2O3 can reach 90.52 %.     

Nanobubble generation and its applications in froth flotation(partⅢ):specially designed laboratory scale column flotation of phosphate

##正##Froth flotation is used widely for upgrading raw phosphate.The flotation recovery of coarse phosphate(-1.18+0.425 mm) is much lower than that achieved on the-0.425+0.15 mm size fraction.Enhanced recovery of coarse phosphate particles is of great economic and environmental importance for phosphate industry.In this investigation,four different phosphate samples were aquired,characterized and tested in a specially designed laboratory-scale flotation column.Significant recovery improvement of coarse phosphate flotation was achieved using cavitation-generated nanobubble though its effects differ among the four testing phosphate samples.The laboratory-scale flotation column test results indicate that nanobubble increased P_2O_5 recovery by up to 10%～30%for a given Acid Insoluble(A.I.) rejection,depending on the characteristic of phosphate samples.The improvement effect of nanobubble on the hard-to-float particles was more significant than that on easy-to-float particles,especially at lower collector dosages.Nanobubbles reduced the collector dosage by 1/3 to 1/2.Nanobubbles almost doubled the coarse phosphate flotation rate constant and increased the flotation selectivity index by up to 25%.     

Original potential flotation of galena and its industrial application

1　ＩＮＴＲＯＤＵＣＴＩＯＮＥｌｅｃｔｒｏｃｈｅｍｉｃａｌｔｅｃｈｎｉｑｕｅｓｈａｖｅｂｅｅｎａｐ ｐｌｉｅｄｉｎｍａｎｙｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｆｓｕｌｆｉｄｅｆｌｏｔａｔｉｏｎｓｙｓｔｅｍｓ,ａｎｄｅｆｆｅｃｔｓａｎｄｃｏｎｔｒｏｌｏｆｐｏｔｅｎｔ     

A series of aminoamides used for flotation of kaolinite

N-(2-aminoethyl)-dodecanamide, N-(3-dimethylaminopropyl)-dodecanamide, and N-(3-diethylaminoproyl)-dodecanamide used as collectors were studied for the flotation of kaolinite in the absence of additives at different pulp pHs as well as different collector contents. The effectiveness of the long chain aminoamides on pure kaolinite was demonstrated in laboratory scale flotation tests. The adsorption mechanism of the aminoamides onto kaolinite was investigated through zeta potential determinations and infrared spectrometry. The -98 μm size fractions of kaolinite, taken from Jiaxian Henan of China, were used in flotation. The hydrophilic group size of the aminoamides has a relatively less influence upon the floatability of pure kaolinite. The results suggest either the static-electric force or the coordinating bond adsorption mechanism of the aminoamides onto kaolinite depends on pulp pH.     

Potential control flotation of galena in strong alkaline media

The electrochemical oxidation of galena in collectorless and collector flotation systems, particularly in strong alkaline media, was studied. The results show that, with pH value higher than 12.5 and potentials below 0.17 V, the oxidation products of galena are elemental sulfur and HPbO2^- . Elemental sulfur was present on the mineral surface in excess of oxidized lead species due to dissolution of HPbO2^- , which is beneficial to the flotation of galena. Under the same conditions, sphalerite and pyrite were depressed as a result of significant surface oxidation. Diethyldithioearbamate (DDTC) was found to be the most suitable collector for galena flotation in strongly alkaline media. The very potential produced hydrophobic PbD2-the surface reaction produet of DDTC with galena, is 0 to 0.2 V. Meantime DDTC can depress the surface over-oxidation of galena.Investigations also indicate that, in the range of - 0.9 V to 0.6 V, hydrophobic PbD2 can be firmly adsorbed on galena.     

Effect of hydroxamic acid polymers on reverse flotation of bauxite

The effect of hydroxamic acid starch (HAS) and hydroxamic acid polyacrylamide (HPAM) on the flotation of diaspore and kaolinite was investigated by flotation test. It is found that HAS depresses diaspore but activates kaolinite in acidic pulp,while HPAM activates both diaspore and kaolinite in the pH range of 2.0 - 10.5. The measurement of zeta potential shows that both HAS and HPAM can increase zeta potential of negatively charged diaspore, which indicates the existence of chemical bonding or hydrogen bonding between the reagents and diaspore.By covering the collector dodecyl amine(DDA) on diaspore surface, HAS increases the hydrophilicity of minerals and depresses the flotation of diaspore,however HPAM activates the flotation of diaspore by increasing the adsorption of DDA on diaspore surface.     

Nanobubble generation and its applications in froth flotation(part Ⅳ): mechanical cells and specially designed column flotation of coal

Coal is the world's most abundant fossil fuel.Coal froth flotation is a widely used cleaning process to separate coal from mineral impurities.Flotation of coarse coal particles,ultrafine coal particles and oxidized coal particles is well known to be difficult and complex.In this paper,the nanobubbles' effects on the flotation of the varying particle size,particle density and floatability coal samples were evaluated using a bank of pilot scale flotation cells,a laboratory scale and a pilot scale specially designed flotation column.The parameters evaluated during this study include the flow rate ratio between the nanobubble generator and the conventional size bubble generator,the superficial air velocity,collector dosage,frother concentration,flotation feed rate,feed solids concentration,feed particle size,and the superficial wash water flow rate,etc.The results show that the use of nanobubbles in a bank of mechanical cells flotation and column flotation increased the flotation recovery by 8%～27% at a given product grade.Nanobubbles increased the flotation rate constants of 600～355,355～180,180～75,and 75～0 microns size coal particles by 98.0%,98.4%,50.0% and 41.6%,respectively.The separation selectivity index was increased by up to 34%,depending on the flotation feed characteristics and the flotation conditions.     

Upgrading graphite by flotation at Bogala Mines in Sri Lanka

ＴｈｅｖｅｉｎｇｒａｐｈｉｔｅｄｅｐｏｓｉｔｓｏｆＳｒｉＬａｎｋａｈａｖｅｂｅｅｎｋｎｏｗｎｔｏｔｈｅｗｏｒｌｄｓｉｎｃｅｔｈｅｙｗｅｒｅｆｉｒｓｔｐｕｔｉｎｔｏｐｒｏｄｕｃｔｉｏｎｉｎ 1 880 .Ｐｅａｋｐｒｏｄｕｃｔｉｏｎｗａｓｍａｒｋｅｄ ,30 0 0 0ｔｏｎｓｐｅｒａｎｎｕｍｄｕｒｉｎｇｔｈｅｐｅｒｉｏｄｓｏｆｌａｓｔｔｗｏｗｏｒｌｄｗａｒｓ .ＴｈｅｎＳｒｉＬａｎｋａｈａｄａｖｅｒｙｇｏｏｄｒｅｐｕｔａｔｉｏｎｆｏｒｉｔｓｈｉｇｈｑｕａｌｉｔｙｎａｔｕｒａｌｇｒａｐｈｉｔｅ .Ｔｈｉｓｒｅｐｕｔａｔ…     

Effects of sodium hexmetaphosphate on flotation separation of diaspore and kaolinite

1INTRODUCTION ThebauxiteinChinaismainlyofdiasporite type,withhighcontentofAl2O3butlowmassra tioofAl2O3toSiO2.Themainsiliceousminerals ofbauxitearekaolinite,illiteandpyrophyllite[1].Inordertoutilizethebauxiteeffectively,anewflotationdesilication Bayermethodwasdeveloped toproducealumina.Thepurposeofflotationdesil icationistoremovethesilicafromthebauxiteandtoincreasethemassratioofAl2O3toSiO2.Funda mentalresearchofreverseflotationdesilicationhas beenpaidmoreattentionduetoitsadvantageover…     

Depressing effect of sodium hexametaphosphate on apatite in flotation of rutile

The separation of rutile from apatite by flotation and the mechanism of depressing the apatite of sodium hexametaphosphate were studied. The results showed that rutile and apatite could be separated by using alkyl-imino-bismethylene phosphoric acid and sodium hexametaphosphate as a collector and a regulator, respectively. Sodium hexametaphosphate could selectively dissolve calcium ions on the apatite surface, and make calcium ions break away from lattice binding through combining.     

Effect of quaternary ammonium salts on flotation behavior of aluminosilicate minerals

The electrokinetic properties and flotation of diaspore,kaolinite,pyrophyllite and illite with quaternary ammonium salts collectors were studied.The results of flotation tests show that the collecting ability of quaternary ammonium salts for the four minerals is in the order(from strong to weak)of octadecyl dimethyl benzyl ammonium chloride(ODBA),cetyl trimethyl ammonium bromide(CTAB),dodecyl trimethyl ammonium chloride(DTAC).Under the condition of alkalescence,it is possible to separate the diaspore from the silicate minerals such as kaolinite,illite and pyrophyllite using quaternary ammonium salts as collector.Isoelectric points(IEP)of diaspore,kaolinite,pyrophyllite and illite are pH=6.0,3.4,2.3 and 3.2,respectively.Quaternary ammonium salts can change ζ-potential of the aluminosilicate minerals obviously.The flotation mechanisms were explained by ζ-potential and Fourier transform infrared spectrum(FT-IR)measurements.The results demonstrate that only electrostatic interaction takes place between aluminosilicate     

A new synthetic chelating collector for the flotation of oxidized-lead mineral

A new synthetic reagent DPTUHP [diphenyl α-（3-phenylthioureido） hexylpbosphonate] containing a hydrocarbon chain nonpolar group, a thioureido, and a phosphonate easter chelating group, has proven to be an effective collector for the flotation of cerussite mineral. The synthetic method utilized the Mannich-type reaction of an N-monosubstituted thiourea, an aldehyde, and triphenyl phosphate in glacial acetic acid solution. The experimental results of flotation of the cerussite mineral show that the collector has stronger collecting ability and higher selectivity in a neutral and a slightly alkaline medium, especially in the pulp of pH=8. Using the measurements by infrared spectroscopy （IR） and X-ray photoelectron spectroscopy （XPS） of the cerussite mineral, the collector, as well as the cerussite treated with the collector, the flotation mechanism of cerussite has been discussed. It is concluded that the adsorption of collector on cerussite is a chemical adsorption through the electron donor atoms of the collector chelating the Pb （ Ⅱ ） of cerussite to form chelate.     

Galvanic coupling and its effect on origin potential flotation system of sulfide minerals

The galvanic coupling formed in origin potential flotation systems of sulfide minerals can be divided into three types: sulfide mineral-sulfide mineral-water system; sulfide mineral-steel ball-water system; and sulfide mineral-sulfide mineral-collector system. In this paper, taking lead, zinc, iron sulfide mineral systems for examples,several models of galvanic coupling were proposed and the effects of galvanic coupling on flotation were discussed. A galvanic contact between galena (or sphalerite) and pyrite contributes to decreasing the content of zinc in lead concentrate, and enhances remarkably the absorption of collector on the galena surface. During grinding, due to galvanic interactions between minerals and steel medium, Fe(OH)3 formed covers on the cathodic mineral surface, affecting its floatability.     

Improvement of copper–molybdenum ore beneficiation using a combined flotation and biohydrometallurgy method

The authors present the results of analysis of material composition and experimental investigations of acid and biohydrometallurgical leaching of middlings on grain size, pH level, leaching process duration, temperature and slurry density. The rational parameters of flotation and acid-bacterial leaching of middlings providing an efficient release of valuable components from mineral complexes and recovery to flotation concentrate and leaching solution have been determined. A combined flowsheet and a beneficiation process for bulk flotation middlings of copper–molybdenum ore have been suggested, which include middlings grinding, sulfide minerals flotation, bacterial leaching of sulfide flotation tailings, liquid-phase extraction of dissolved copper and electrolysis of re-extraction eluates. The suggested combined method of cleaning of middlings of copper–molybdenum ores beneficiation provides the total copper recovery increase by 0.8% with a reduction of the cost price of saleable material by 0.5%.     

Improved recovery of a low-grade refractory gold ore using flotation–preoxidation–cyanidation methods

In this work, different flotation–preoxidation–cyanidation methods are considered for treating a low-grade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1% of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.     

Adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings

The adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings. The adsorption percentage of Pb^2＋ and Cd^2＋ ions as a function of adsorbent dosage, solution pH value and shaking time were determined by batch experiments. The maximum adsorption percentage of 99.93% for Pb^2＋ ions and 99.75% for Cd^2＋ ions were obtained by using bauxite flotation tailings as adsorbent. The methods, such as zeta potentials, specific surface area measurements and the analysis of adsorption kinetics, were introduced to analyze the adsorption mechanisms of the Pb^2＋ ions on bauxite flotation tailings. The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb^2＋ ions. The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m^2/g after the adsorption of Pb^2＋ ions. These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings. Adsorption data of Pb^2＋ ions on the surface of bauxite flotation tailings can be well described by Langmuir model, and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings.