Adsorption of dithiophosphate and dithiophosphinate on chalcopyrite

Electrochemical behavior of chalcopyrite was investigated in the absence and presence of dithiophosphate (DTP) and dithiophosphinate (DTPI), selective thiols against Fe-sulfides in the flotation of sulfide ores, in potentiostatically controlled electrochemical condition. Diffuse reflectance Fourier transformation (DRIFT) spectroscopy was applied to determine the type of adsorbed collector species, and Hallimond tube flotation tests were performed to clarify the role of polarization potential and thiol collectors on the floatability of chalcopyrite. DRIFT spectroscopy study proposed that dithiolate of DTP, (DTP)₂, was the major surface compound formed under oxidizing potentials in slightly acidic and neutral conditions. However, DTP species formed on mineral surface in alkaline condition could not be determined possibly due to heavy surface coating of metal oxyhydroxides. DTPI species formed on chalcopyrite was found to be in the form of CuDTPI + (DTPI)₂. Additionally, presence of adsorbed DTPI, DTPI⁰, was also detected. Self-induced floatability was significantly high particularly in slightly acidic condition and decreased by increasing pH due to surface coating of metal oxyhydroxides. Addition of both collectors improved the flotation performance at all pH values. However, the positive effect of DTP at high alkaline pH values was lower than that of DTPI. This was attributed to weak collecting property and lower hydrocarbon chain length of DTP compared to DTPI. Effect of pulp potential could not be observed in slightly acidic condition, but it became apparent at higher pHs. Although better flotation responses were obtained in mildly oxidizing potentials, both collectors enlarged the floatability potential range of chalcopyrite.     

Scientific grounds for high-performance agent modes in platiniferous sulfide mineral flotation from rebellious ores

The author substantiates the choice of new selective agents PTTC, HPEDETC, and Hostaflot M-91 to float platiniferous sulfide minerals from rebellious ores. The study agent modes imply the use of PTTC, being a component of modified xanthate and providing 6–7% increase in recovery of copper, nickel, and PGM in flotation of the low-sulfide platiniferous copper-nickel ore from the Fedorovo-Pansky deposit. The substitution of HPEDETC and Hostaflot M-91 for xanthate makes it possible to increase recovery of platinum by 5.7–13%, palladium by 4–9% and 2–4 times the noble metal content in the flotation concentrate.     

Use of fluorinated alcohols to intensify copper-nickel ore grinding

The experimental data are reported on intensification of the copper-nickel grinding by feeding fluorinated saturated mono-atomic alcohols of a general formula H - (CF₂CF₂) _n - CH₂ - OH into a mill. The feeding of this reagent into a mill at the rate of 25–100 g/t of feed provides better exposure of aggregates in the ore preparation circuit thus intensifying the subsequent ore flotation. The increment of copper and nickel recovery into a concentrate amounts to more than 4%. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 95–100, July–August, 2008.     

New experimental evaluation techniques for selectivity of collecting agents for gold and platinum flotation from fine-impregnated noble metal ores

It is proposed to apply nanosize Au and Pt particles to ground mineral particles for the analysis of flotation and adsorptive properties of new reagents. The authors have obtained specimens of pyrite, arsenopyrite and quartz artificially enriched by nanosize gold particles. Reductive adsorption from Na₂[PtCl₆] and Na[AuCl₄] produced pyrrhotine uniformly applied with microsize platinum particles. The article discusses the application range of the proposed techniques and methods of examination of specimens and interaction between reagents and micro- and nanosize gold and platinum particles depending on the conditions of sulfide treatment by the noble metals and on properties of a host mineral. Advanced integrated analysis of interaction between the nitrogen-bearing reagent MTKh and gold confirmed chemically induced selectivity of MTKh towards gold     

Behavior and effect of calcium during hydrothermal sulfidation and flotation of zinc-calcium-based neutralization sludge

Neutralization sludge (NS), a calcium-based heavy metal waste, was produced in large quantities during wastewater treatment using lime milk neutralization in the nonferrous metal industry. During hydrothermal sulfidation and flotation of NS, the phase transition of calcium compounds might play a crucial role in the subsequent flotation for low metal recovery. During hydrothermal sulfidation, calcium minerals in NS were converted and further developed into bulk CaSO₄ crystals with many nano-ZnS crystals adhering on its surface. Specifically, the conversion of CaCO₃ into CaSO₄ could accelerate the sulfidation of NS. However, the presence of CaSO₄ could slow the growth rate of ZnS crystals, which imposes a negative effect on subsequent flotation. CaSO₄ crystals with irregular shapes and incomplete crystallization combined with nano-ZnS crystals were frequently observed in concentrates after flotation, whereas CaSO₄ crystals of regular shape and high crystallinity were mainly discovered in tailings, indicating that modifying the crystalline nature and texture of CaSO₄ crystals is a feasible method for separating ZnS and CaSO₄ and for increasing metal recovery. Furthermore, the adsorption of collectors on CaSO₄ was hardly detected, indicating that CaSO₄ barely competed with ZnS for collectors during flotation.     

Experimental-analytical methods of the investigating the effect of complexing reagents on platinum flotation

The paper considers the studies into the hydrophobic properties of platinum and platinum arsenide, sperrylite, in the solution with added complexing reagents by using the method of measuring the force of the air bubble abstraction from the mineral surface. The effect of these complexing reagents on the chemical properties of sperrylite and pyrrhotine is analyzed. A new-developed procedure for treatment of pyrrhotine by chloroplatinic acid is presented, and the comparative flotation of natural pyrrhotine and platinum-pretreated pyrrhotine with the complexing reagents is described. The collecting properties of diisobutyl dithiophosphinate for platinum are determined, and the use of this reagent as an additional collector for platinum-group metals is confirmed in the course of the experimental flotation of platinum-bearing copper-nickel ore samples. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 68–75, May–June, 2008.     

Electrochemical interactions of industrially important platinum-containing minerals

Pt–Te₂ and Pt–Bi–Te are two important platinum-carrying minerals typically found in altered platinum reserves. Mineralogical studies indicate the Pt–Pd–Bi–Te class to react poorly on the flotation stimuli and indications are that these minerals are slow floaters. This paper investigates the fundamental interactions of potassium ethyl xanthate with these minerals by employing electrochemically controlled contact angle measurements, FT-IR spectroscopy and voltammetry. The electrochemical investigations revealed that Pt–Te₂ is more noble than Pt–Bi–Te at potentials lower than 300 mV (SHE) in sodium tetraborate buffer solution and the reduction peak observed during the return sweep of Pt–Bi–Te is mainly associated with the reduction of bismuth oxidation products. Both the minerals show increased anodic currents when polarised at 0.3 V (SHE) in a 0.05 M Na₂B₄O₇ solution containing 1 × 10⁻³ M potassium ethyl xanthate. According to the results of the rest potential measurements, formation of dixanthogen should be thermodynamically favourable and the very high rest potentials are attributed to the catalytic effect of platinum on the oxygen reduction reaction. The formation of dixanthogen on both the minerals was confirmed by ex situ FT-IR spectroscopy. Contact angle measurements revealed the surface of Pt–Bi–Te to be hydrophobic in nature whereas small contact angles were realized on Pt–Te₂. Surface roughness of the mineral could be responsible for these small contact angles.     

Extraction of hydrogen cyanide from waste solutions of cyaniding circuit for sulfide flotation concentrates

The process for extraction of hydrogen cyanide to decontaminate solutions produced at cyaniding of sulfide flotation concentrates is developed. The centrifugal-bubbling apparatus is employed as a reactor. The regularities of HCN formation in an acid medium are established in investigation into kinetics of SCN⁻ thiocyanate oxidation by hydrogen peroxide H₂O₂ in presence of Fe²⁺, Fe³⁺ and pH ≤ 3.5. In the process proposed the evolved HCN is adsorbed by NaOH solution and returned to the circuit of leaching of gold and silver as NaCN, and the waste cyaniding solution is discharged into a waste dump, where it is mixed with industrial water to be utilized to transport flotation tailings. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 98–105, January–February, 2009.     

Non-traditional high-energy processes for disintegration and exposure of finely disseminated mineral complexes

For the first time the modern non-traditional processes for treatment of rebellious noble metal-bearing mineral ore, aimed at improving disintegration efficiency for finely dispersed mineral complexes are analyzed. Advantages and perspectives of a new high-efficient, energy-saving and ecologically safe process of the nanosecond powerful electromagnetic impulse (PEMI) effect, are proved. The said process provides a stable increase in the valuable component recovery at lower energy consumption and production costs of the finite product at the stage of dressing rebellious gold-bearing ores and concentrated products. The possible mechanisms of mineral disintegration under PEMI effect are considered, experimental data, cited in the paper, prove high efficiency of the preliminary impulse treatment, thus, the increase in the gold recovery at the cyanidation stage amounted to 4–12 % from rebellious ores, 10–30 % from gravity concentrates, 5–45 % from flotation concentrates, 30–80 % from oil flotation tailings. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 107–128, May–June, 2007.     

A review of hematite flotation using 12-carbon chain collectors

A sample of naturally occurring, relatively pure hematite (98.5% Fe₂O₃) was used as a model for the study of the flotation of insoluble metal oxides. The isoelectric point of this sample was 2.7 and the point of zero charge was 6.7. A number of surfactants containing saturated 12-carbon chain groups were used as collectors over a wide range in pH.The flotation of this hematite with dodecanoic acid (lauric acid) showed a maximum recovery in the pH range 6–8.5, a sudden drop at pH 9, and a steady increase in recovery as the pH was raised from 9–12. The flotation of the hematite using potassium dodecyl hydroxamate showed a maximum recovery at pH 5.5, with little flotation at pH <3. AtpH >10, the recovery fell except at high additions of collector. The flotation of hematite using sodium dodecyl sulphate showed a high recovery for pH <6, a trough in recovery between pH 7 and 9, and a secondary maximum in recovery at pH 10. Different flotation behaviour was observed when sodium dodecyl benzyl sulphonate was used. Using ARMAC C, (a commercially available dodecyl ammonium acetate), a flotation maximum was observed at pH 8, with steadily decreasing recovery as the pH was raised or lowered from this value. These results are discussed in terms of the surface chemistry of the hematite and the solution chemistry of the various collectors used.     

Reynolds number in restricted movement of mineral grains

Conclusions The authors determine the conditions of similarity for restricted motion of grains in a stream at constant velocity which are common with the conditions for free motion governed by the similarity rule of Reynolds. In the Reynolds number for restricted conditions, the characteristic parameter should be a linear quantity characterizing the thickness of the layer of liquid diverted by the body. In this case the relation between the coefficient of resistance ψ_re and the Reynolds number Re _l for restricted conditions takes the form of straight-line graphs passing through points on the Rayleigh curve corresponding to ψ₀ and Re₀ for free motion of the grains. These relations permit us to take detailed account of the variation in the degree of mutual influence between the grains in relation to their hydraulic dimensions. The expression for restricted motion of grains, based on the relation ψ_re =f(Re _l ), embraces the whole possible range of degrees of dilution of the grains and can be used in practical calculations. Mekhanobrchermet, Krivoi Rog. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 90–98, September–October, 1974.     

Effect of impeller rotational speed on the size dependent flotation rate of galena in full scale plant cells

The first three rougher cells in the lead circuit of the Elura concentrator (formerly Pasminco Australia Limited) were selected as the plant cells for investigation. Metallurgical surveys were performed and various hydrodynamic measurements taken, allowing the galena flotation rate constant and the bubble surface area flux (S_b) in these cells to be calculated over a wide range of gas flow rates, and at two impeller rotational speeds. It was determined that altering the impeller rotational speed did not significantly change the rate constant dependency on S_b when flotation was considered on an unsized basis.The analysis was further extended to examine the same cells parameters on a size-by-size basis. The results obtained have been used to identify differences in the flotation behaviour of the various particle size fractions, independently of surface hydrophobicity. It is shown that the physical conditions for effective flotation of fine (<9 μm) and coarse (>53 μm) particle size fractions differ substantially, suggesting that a specific hydrodynamic environment will favour a high flotation rate for fine galena, which may be detrimental to the recovery of coarse galena, and vice versa. These observations are in accord with metallurgical practice that suggest that it is difficult to improve fine particle flotation without also compromising coarse particle stability efficiency simply by modifying the cell hydrodynamics alone. A fundamental flotation model was applied to quantify differences in the flotation rate of the various particle size fractions with impeller rotational speed.     

Flotation kinetics equations and transfer functions for flotation machines taking account of the effect of the froth layer

Conclusions Flotation kinetics equations and transfer functions have been obtained for a two-phase flotation model. It has been demonstrated that specific flotation rate depends on concentration of minerals being floated in the froth layer. Sverdlovsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki poleznykh Iskopaemykh, No. 4, pp. 107–111, July–August, 1984.     

Application of complexing reagents to flotation separation of the varieties of pyrite

It is considered how the organic reagents, complexing agents, change floatability of the varieties of pyrite with different content of goal. The authors continue studying the flotation effect of the reagent PROX capable to selectively decrease floatability of some pyrite varieties in the presence of xanthogenate due to formation of a hydrophilic complex compound with ferric iron at the phase interface of the mineral surface — liquid, and to reduce sorption of xanthogenate. A phytogenous reagent is suggested as an alternative to the multi-component PROX. The new reagent mechanism is described by examining the chromatographic behavior of the compound of this reagent and ferric iron salt. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 111–120, July–August, 2007.     

The flotation chemistry of potassium double salts: Schoenite,kainite, and carnallite

It is known from soluble salt flotation practice that the K, Mg double salts of kainite (KClMgSO₄3H₂O), and carnallite (KClMgCl₂6H₂O) are difficult to float and must be converted to other salts such as schoenite (K₂SO₄MgSO₄6H₂O) and sylvite (KCl) in order to recover potash values. The flotation characteristics of these double salts have now been confirmed in some detail by carefully controlled laboratory experiments with both cationic and anionic collectors. The experimental results are discussed in view of recent experimental findings regarding the flotation characteristics of simple salts, in which the flotation response was shown to be determined by the interfacial water structure and whether the salt could be considered to be a water structure maker or a water structure breaker. The same approach can be use to explain the flotation response of the potassium double salts; schoenite, kainite, and carnallite.In addition, the sign of the surface charge of schoenite (K₂SO₄MgSO₄6H₂O), was determined as a function of pH from nonequilibrium electrophoretic mobility measurements. Schoenite appears to exhibit three charge reversals (CR) which can be explained based on surface hydrolysis reactions. The flotation behavior of schoenite is further considered based on solution chemistry calculations, electrophoretic mobility measurements, and microflotation results.     

Specifics of the sulfuric-acid processing of galena concentrates in the presence of nitrous acid

Conclusions  

Response of rough and acute surfaces of pyrite with 3-D approach to the flotation

This study presents a new 3-D approach to determine the morphological properties of pyrite particles by Brunauer — Emmett — Teller (BET) nitrogen gas adsorption and Permaran methods. The obtained parameters, which are surface roughness and acuteness, were correlated with the floatability of those mineral particles. The flotation performances of the pyrite particles ground in different mills were also evaluated by a Hallimond tube. The results showed that lower roughness and acuteness values caused higher flotation recoveries for the pyrite particles considered. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 95–104, July–August, 2006     

Physically sorbed collectors in froth flotation and their activity. Part II

The mechanism of the physically sorbed collector in froth flotation is under discussion in the paper. It is shown that the basic characteristics of the collecting capacity of a physically sorbed flotation agent are its solubility, surface pressure in the film of the agent at “gas-liquid” interface, and viscosity. Experimental data and practical evidence described in the paper fortify the proposed mechanism of the collecting agent under consideration. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 85–95, March–April, 2009.     

Influence of bromine modification on collecting property of lauric acid

Bromine atom with strong electronegativity was introduced to α-carbon position of lauric acid (LA) by solvent-free method (Hell–Volhard–Zelinski reaction) at ambient pressure in laboratory, and the synthesized product α-Bromolauric acid (CH₃(CH₂)₉CHBrCOOH, α-BLA) was used as a new type collector for the flotation of quartz mineral. The flotation properties of pure quartz using α-BLA as a collector were investigated by single mineral flotation tests. The adsorption mechanism of α-BLA collector on quartz surface was established by zeta potential measurements, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), in conjunction with the results of quartz micro-flotation tests. Pure mineral flotation results showed that the collector α-BLA exhibited an excellent performance at alkaline conditions (pH ⩾ 11.50), activator CaCl₂ concentration 1.0 × 10⁻⁴ mol/L, and collector concentration 1.5 × 10⁻⁴ mol/L in a relatively lower temperature 15 °C, where about 99.8% of the quartz could be floated out. Compared with collector LA, the new synthesized collector α-BLA is more tolerant to lower pulp temperature and fluctuations of the reagents dosages. The study revealed that the α-BLA collector had adsorbed on the surface of pure quartz in the forms of chemical interaction, electrostatic adsorption and hydrogen bonding adsorption based on the results of zeta potential measurements, FT-IR spectra, and XPS.     

Theoretical basis for optimal collector concentrations and pulp pH values during flotation of sulfide-free minerals

A hypothesis that associates optimal conditions of mineral flotation with a zero charge of their surface is put forward. This hypothesis serves as a basis for a methodology to obtain and verify quantitative physical-chemical models for a minimal necessary concentration of a collector during flotation of sulfide-free minerals. These models may be of use for upgrading engineering processes of flotation and as a job for the concentration plant automation systems. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 89–99, March–April, 2006.