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Abstract: In the present investigation the relationship between collection zone rate constant (k c) and gas dispersion parameters, viz. bubble size (d b), superficial gas velocity (J g), gas hold-up (ε g) and bubble surface area flux (S b) was evaluated. Experiments were conducted in an industrial (4m in diameter and 12m high) and a pilot (0.1m in diameter and 4m high) flotation column in rougher circuit at Miduk copper concentrator in Iran. Gas hold-up was measured using pressure difference technique and mean bubble sizes were estimated from a drift flux analysis. It was found that the collection zone rate constant was not correlated with d b and J g solely but was linearly dependent on ε g and S b for the range of interest. Collection efficiency (E k) and floatability factor (P) in the industrial columns were quantified (E k =3.1%; P =7.7×10−3). The influence of operating parameters comprising superficial gas velocity, slurry solids% and frother dosage/type on S b and flotation kinetics was discussed. Analysis of available industrial data suggested that S b and ε g were related by S b =4.46ε g over the range 30< S b <60s−1 and 7%< ε g <14%. [Copyright &y& Elsevier]

Abstract: In this investigation the froth zone of an industrial column (4m “diameter”×12m “height”) in rougher circuit was characterized. Experiments were carried out at Miduk copper concentrator, Iran. Miduk is a unique copper processing plant which utilizes columns in rougher circuit. Cleaning and selectivity actions in the rougher froth were illustrated using solids and grade profiles along with RTD data. The impact of froth depth (FD) on overall rate constant (k) and k–S b relationship was evaluated. Dependency of overall flotation kinetics on froth depth and gas velocity (J g) was modeled by k =4.97(FD)−0.87(J g)0.80. Froth recovery (R f) was estimated and modeled in terms of froth residence time of slurry (FRTSlurry) as R f = R f,maxexp(−k ×FRTSlurry). Finally, the correlation between k, S b (indicative of the collection zone performance) and FRTSlurry (indicative of the froth zone performance) was modeled by k =0.02 (FRTSlurry)−0.62(S b)0.82. [Copyright &y& Elsevier]

Abstract: In this investigation, a pilot-scale flotation column was successfully designed, installed and tested in rougher circuit of the Miduk copper concentrator, Iran. The axial dispersion model was employed in the design procedure. Collection zone rate constant (k c) along with the target recovery of over 75% was used to size the column. The rate constant k c was determined based on a number of pilot and industrial experiments. Performance of the pilot column was compared with existing full-scale Microcel columns in a number of parallel experiments. [Copyright &y& Elsevier]

Thiobacillus Ferrooxidans bacteria are commonly used for bio-leaching and recently in biobeneficiation of sulfide minerals. In this study, the effect of Thiobacillus Ferrooxidans on the froth flotation behavior of Sarcheshmeh copper ore in Iran has been investigated. Pure strains of Thiobacillus Ferrooxidans were used to promote surface chemical changes in pyrite and chalcopyrite, and thus influence their flotation behavior.In the presence of Thiobacillus Ferrooxidans, and xanthate as collector, pyrite was depressed, whereas chalcopyrite and other sulfide minerals were unaffected at natural pH. The present investigation shows that the surface chemical properties of bacteria can be manipulated successfully to achieve the desired effects on the flotation process. The results showed that recovery of pyrite in the presence of a depressant (Thiobacillus Ferrooxidans) is 50% lower than in the absence of any bacteria, demonstrating the depressing effect of bacteria on pyrite. It was concluded that the use of Thiobacillus Ferrooxidans would decrease the recovery of pyrite but would not changed the floatability of chalcopyrite. [Copyright &y& Elsevier]