Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. II. Galena and pyrite surfaces

Gardner, JR; Woods, R.

doi:10.1071/ch9770981

Cited by 68 publications

(20 citation statements)

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“…In the elec tro chem i cal mech a nism, elec trode re ac tions oc cur on the ga lena sur face which is in con tact with the aque ous so lu tion con tain ing xanthate ion, as fol lows 15 …”

Section: Introductionmentioning

confidence: 99%

Electrochemical depression of galena aiming at selective sulfide flotation

Dutra¹,

Espinola²,

Sampaio³

1997

J. Braz. Chem. Soc.

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Neste artigo, o potencial no qual a depressão da ga lena ocorre, é relacionado com a formação de compostos hidrofílicos em sua superfície. São propostas reações com base em voltametria cíclica, da dos termodinâmicos e análises por espectroscopia de fotoelétrons. Variáveis eletroquímicas, tais como o potencial de oxirredução, apresentam boas perspectivas para a flotação seletiva da ga lena e esfalerita, pois numa dada faixa de potencial, a superfície da ga lena, ao contrário da esfalerita, se torna hidrofílica, conforme mostraram as medidas de ângulo de contato e tes tes de microflotação.In this ar ti cle, the po ten tial at which ga lena de pres sion oc curs is re lated to the for ma tion of hy dro philic com pounds on its sur face. Re ac tions are pro posed based on anal y ses by cy clic voltammetry, ther mo dy namic data, and X-ray pho to elec tron spec tros copy (XPS). Elec trochem i cal vari ables, such as the re dox po ten tial, pres ent good per spec tives for se lec tiv ity in the flo ta tion of ga lena and sphalerite, be cause in a given range of po ten tials, the ga lena sur face becomes hy dro philic, as shown by mea sure ments of the con tact an gle and floatability tests. Key words: ga lena elec tro chem is try, con tact an gle, de pres sion, sphalerite In tro duc tionThe flo ta tion of sul fide min er als, us ing ore with complex com po si tion, has been ex ten sively stud ied, as shown by lit er a ture re views; the pur pose is to ob tain se lec tiv ity in the pro cess [1][2][3][4] . Some de pres sants and ac ti va tors are al ready well known, such as cy a nide and zinc sul fate. In cases of mix tures of lead, cop per, and zinc min er als , the se lec tiv ity is poor, and the lead con cen trates be come highly con tam inated by the other min er als which orig i nate from the lead ore.The main lead ore is lead sul fide, ga lena, with a the o reti cal con tent of 86 wt% Pb. It oc curs nat u rally, ac com pa nied by other sul fides and gangue min er als. The clas sic pro cess of ore dress ing ap plies thiocollectors, such as xan thates, in a pH range of 8 to 9; the re sult ing con cen trate is 60% Pb 5,6 . How ever, the mech a nism of the re ac tion has not yet been solved 7,8 . The old est the ory 9 ex plains the pro cess as one of ad sorp tion, with ion ex change be tween the an ions xanthate and sul fide oc cur ring on the sur face of the min eral. It is widely rec og nized that ox y gen is es sen tial to the flo ta tion pro cess 10-14 .In the first step of the chem i cal mech a nism, the ga lena sur face sul fide ion is ox i dized, pro duc ing lead sul fate and thiosulfate, and the lat ter re acts with xanthate ion X -, as follows The hy dro pho bic char ac ter of the ga lena sur face is attrib uted to PbX2.In the elec tro chem i cal mech a nism, elec trode re ac tions oc cur on the ga lena sur face which is in con tact with the aque ous so lu tion con tain ing xanthate ion, as fol lows 15 : Ar ti cle

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“…In the elec tro chem i cal mech a nism, elec trode re ac tions oc cur on the ga lena sur face which is in con tact with the aque ous so lu tion con tain ing xanthate ion, as fol lows 15 …”

Section: Introductionmentioning

confidence: 99%

Electrochemical depression of galena aiming at selective sulfide flotation

Dutra¹,

Espinola²,

Sampaio³

1997

J. Braz. Chem. Soc.

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“…Resultados similares de ângulo de contato foram obtidos no trabalho de Gardner et al 29 Fuerstenau et al 26 , calcularam, para vários xantatos de cadeias carbônicas diferentes, o número de moléculas necessárias para cobrir com uma monocamada toda a área superficial das partículas de galena (PbS). Eles assumiram que a cada cela unitária dois átomos de chumbo estão disponíveis para interação e que apenas uma molécula do xantato se adsorve sobre um átomo de chumbo.…”

Section: Resultados E Discussão Isotermas De Adsorção âNgulo De Contunclassified

Adsorção de xantatos sobre pirita

2001

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Recebido em 18/7/00; aceito em 22/1/01 ADSORPTION OF XANTHATE ON PYRITE. This paper presents a study of adsorption of xanthate with alkyl chain of two (C 2 XK), four (C 4 XK) and eight (C 8 XK) atoms of carbon, on pyrite from Santa Catarina, Brazil. The results showed that pyrite surface changes from hydrophilic to hydrophobic when xanthate is adsorbed increasing the contact angle to 35 o for C 2 XK, and to 90 o for C 4 XK and C 8 XK. The rate of flotation of pyrite particles after adsorption increases with the increase of the number of carbon atoms in the alkyl chain in agreement with the results of contact angle measurements.

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“…Without CuSO 4 (squares), the recoveries of pyrite were between 80% and 88% at the pH range 4-10, and 59% at pH 12. Pyrite normally has a good floatability with a xanthate collector at low pH, due to the formation of dixanthogen and iron xanthate compounds which render the mineral hydrophobic [1,2]. At 2.5 × 10 −5 M of CuSO 4 (triangles), the recoveries of pyrite increased to values between 88% and 92% at pH range 4-10, and 79% at pH 12.…”

Section: Flotation and Bioflotation Of Cu-activated Pyritementioning

confidence: 99%

“…As a result, pyrite appears in the froth, diminishing the quality of the concentrate. Pyrite reacts naturally with xanthate collectors at low pH with the formation of dixanthogen and ironxanthate over its surface [1][2][3]. However, at high pH, the absorption of xanthate is not as significant as at low pH, so pyrite recovery is lower making possible its separation from copper sulfide minerals which are able to float at high pH values [2].…”

Section: Introductionmentioning

confidence: 99%

Biodepression of Copper-Activated Pyrite with Acidithiobacillus ferrooxidans in Flotation with Fresh and Seawater

et al. 2021

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Acidithiobacillus ferrooxidans has been shown to be a good depressant of pyrite in freshwater and seawater flotation. However, the effect of these bacteria over copper-activated pyrite has not been studied. At the industrial scale, the activation of pyrite with copper is a common process that occurs because Cu2+ ions, released from other minerals, react with pyrite. This is a problem because Cu2+ ions facilitate the reaction of pyrite with the xanthate collectors, becoming hydrophobic and reaching the froth. In this study, microflotation experiments in a Hallimond tube were conducted to evaluate the depressant effect of A. ferrooxidans over non-activated and Cu-activated pyrite in freshwater and seawater flotation. The experiments were carried out at pH 4, 6, 8, 10 and 12 and pyrite was mixed with CuSO4 at 2.5×10−5 and 5×10−5 M in order to activate its surface. Considering the results obtained in the microflotation tests, it is possible to conclude that Acidithiobacillus ferrooxidans is able to depress non-activated and Cu-activated pyrite at the entire pH range studied (4–12) in freshwater. On the other hand, the use of bacteria in flotation with seawater proved to be effective to depress non-activated and Cu-activated pyrite at pH 8 and 10 with better results achieved at pH 10. At this pH, the non-activated pyrite recovery dropped from 96% to 15%, and the recovery of Cu-activated pyrite dropped from 95% to 32% when the activation was carried out at 2.5×10−5 M, and from 87% to 50% when the activation was conducted at 5×10−5 M of CuSO4. The XPS analysis showed that chalcopyrite and copper (II) hydroxide were formed on the pyrite surface when it is contacted with CuSO4.

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Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. II. Galena and pyrite surfaces

Cited by 68 publications

References 0 publications

Electrochemical depression of galena aiming at selective sulfide flotation

Electrochemical depression of galena aiming at selective sulfide flotation

Adsorção de xantatos sobre pirita

Biodepression of Copper-Activated Pyrite with Acidithiobacillus ferrooxidans in Flotation with Fresh and Seawater

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