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The experience gained in the use of flotation columns in rougher circuits is described based on the results obtained at the Sarchesmeh and Miduk Cu concentrators in Iran. The columns are more sensitive to variations in ore composition, liberation characteristics and process variables such as pH, slurry solids % and reagent dosage than mechanical cells. Slimes in the rougher circuit feed could intensify column sensitivity and reduce performance. Flotation columns need to be under precise and continuous control. They are less efficient at recovering coarse particles and only liberated fine particles are can be expected to be recovered, with coarse particles reporting to tailings. The selective nature of columns means that high recovery can rarely be achieved. Conditioning reagents can be added directly to mechanical cells but an agitated conditioner tank is required prior to rougher column flotation., The experience gained in the use of flotation columns in rougher circuits is described based on the results obtained at the Sarchesmeh and Miduk Cu concentrators in Iran. The columns are more sensitive to variations in ore composition, liberation characteristics and process variables such as pH, slurry solids % and reagent dosage than mechanical cells. Slimes in the rougher circuit feed could intensify column sensitivity and reduce performance. Flotation columns need to be under precise and continuous control. They are less efficient at recovering coarse particles and only liberated fine particles are can be expected to be recovered, with coarse particles reporting to tailings. The selective nature of columns means that high recovery can rarely be achieved. Conditioning reagents can be added directly to mechanical cells but an agitated conditioner tank is required prior to rougher column flotation.

The Miduk concentrator in Iran uses column flotation cells as rougher cells. In relation to the high silica contents of the rougher and final concentrates, a project was carried out to optimise the wash water system. This was achieved by increasing the cross-sectional area of the orifices through an increase in their number and by inverting their orientation from upward to downward. The modifications increased the purity of the rougher and final concentrates. Bias rate measurements showed that negative bias and short-circuiting of the wash water into the concentrate launder were the main causes of improper froth-zone washing in the original system., The Miduk concentrator in Iran uses column flotation cells as rougher cells. In relation to the high silica contents of the rougher and final concentrates, a project was carried out to optimise the wash water system. This was achieved by increasing the cross-sectional area of the orifices through an increase in their number and by inverting their orientation from upward to downward. The modifications increased the purity of the rougher and final concentrates. Bias rate measurements showed that negative bias and short-circuiting of the wash water into the concentrate launder were the main causes of improper froth-zone washing in the original system.

This study shows that agglomeration and bioleaching can be used to extract copper from fine-grained low-grade sulphide copper ores. Column bioleaching test results for ore from Sarcheshmeh, Iran, which averages 0. 22% Cu with 30% in the 50% of particles finer than 1 mm and with a high clay content, showed that heap bioleaching for 200-250 days was suitable. Lime and sulphuric acid binders achieved the best agglomerate and column tests for 105 days extracted 77.5% of Cu, compared with 57% in a non- biological control column., This study shows that agglomeration and bioleaching can be used to extract copper from fine-grained low-grade sulphide copper ores. Column bioleaching test results for ore from Sarcheshmeh, Iran, which averages 0. 22% Cu with 30% in the 50% of particles finer than 1 mm and with a high clay content, showed that heap bioleaching for 200-250 days was suitable. Lime and sulphuric acid binders achieved the best agglomerate and column tests for 105 days extracted 77.5% of Cu, compared with 57% in a non- biological control column.

The use was investigated of bioleaching to remove Cu from Sarcheshmeh, Iran, molybdenite concentrate containing Cu 0.83 wt% as chalcopyrite using a native strain of Acidithiobacillus ferrooxidans. Up to 65% of the Cu content was removed in less than 15 days. Additions of ferrous sulphate, sulphur or pyrite were made to the culture medium to enhance the activity of the bacteria, with sulphur giving the best results. Tests using 9K or Norris medium as the culture medium showed that the latter was preferred, and is also less expensive., The use was investigated of bioleaching to remove Cu from Sarcheshmeh, Iran, molybdenite concentrate containing Cu 0.83 wt% as chalcopyrite using a native strain of Acidithiobacillus ferrooxidans. Up to 65% of the Cu content was removed in less than 15 days. Additions of ferrous sulphate, sulphur or pyrite were made to the culture medium to enhance the activity of the bacteria, with sulphur giving the best results. Tests using 9K or Norris medium as the culture medium showed that the latter was preferred, and is also less expensive.

The leaching was investigated of Al from bauxite containing less than 50% Al2O3 obtained from the Jajarm plant, Iran. Analytical studies indicated that silicate and aluminosilicate minerals were the major mineral components and showed the presence of Fe, SiO2 and Ti. Leaching tests were carried out with the indigenous fungi Aspergillus niger and Penicillium notatum using savored dextrose chloramphenicol agar as the medium. A high concentration of Al (7.08 g/l Al2O3) was obtained using a mixture of choleric acid and the fungal metabolites at a 15% bauxite pulp density. Pre-heating of the bauxite enhanced the leaching of Al and inhibited the leaching of Fe., The leaching was investigated of Al from bauxite containing less than 50% Al2O3 obtained from the Jajarm plant, Iran. Analytical studies indicated that silicate and aluminosilicate minerals were the major mineral components and showed the presence of Fe, SiO2 and Ti. Leaching tests were carried out with the indigenous fungi Aspergillus niger and Penicillium notatum using savored dextrose chloramphenicol agar as the medium. A high concentration of Al (7.08 g/l Al2O3) was obtained using a mixture of choleric acid and the fungal metabolites at a 15% bauxite pulp density. Pre-heating of the bauxite enhanced the leaching of Al and inhibited the leaching of Fe.

The mineralogy and processing potential of an Iranian zircon ore was investigated. The ore grades 1-1.1% zircon and contains other potentially valuable Nb-Ta, Ti and REE minerals.. Beneficiation of the ore by gravity and magnetic and heavy liquid separation was tested, using a Humphreys spiral, multi-gravity, dry and wet high-gradient magnetic separation and a clerici-kerosene dense medium. The final recovery was 79% at a grade of 75% zircon., The mineralogy and processing potential of an Iranian zircon ore was investigated. The ore grades 1-1.1% zircon and contains other potentially valuable Nb-Ta, Ti and REE minerals.. Beneficiation of the ore by gravity and magnetic and heavy liquid separation was tested, using a Humphreys spiral, multi-gravity, dry and wet high-gradient magnetic separation and a clerici-kerosene dense medium. The final recovery was 79% at a grade of 75% zircon.

The statistical design of experiments approach was used to investigate the beneficiation of Marzan-Abad zircon ore from northern Iran. The ore has a zircon grade of 0.8% and contains other minerals such as sphene, rare earth element oxides, Nb-Ta and Ti. Beneficiation tests were carried out using shaking-table, multi-gravity, wet and dry high-gradient magnetic separators and heavy liquid separation. The final concentrate was a product with a zircon grade of 85% and with 80% total recovery. The results were used to develop a laboratory scale flow-sheet for the beneficiation process., The statistical design of experiments approach was used to investigate the beneficiation of Marzan-Abad zircon ore from northern Iran. The ore has a zircon grade of 0.8% and contains other minerals such as sphene, rare earth element oxides, Nb-Ta and Ti. Beneficiation tests were carried out using shaking-table, multi-gravity, wet and dry high-gradient magnetic separators and heavy liquid separation. The final concentrate was a product with a zircon grade of 85% and with 80% total recovery. The results were used to develop a laboratory scale flow-sheet for the beneficiation process.

The low-grade Iranian ore contains pyrite, which causes some problems in the flotation of chalcopyrite and other sulphide minerals. It was shown in experiments that selective flotation of the copper sulphides is possible when they interact with Acidithiobacillus ferrooxidans grown in the presence of either natural ferrous ion or sulphur. The bacteria did not adhere significantly to the chalcopyrite but could selectively adhere to the surface of pyrite, hindering its flotability and acting as a depressant. Cells strongly adsorbed on the pyrite surface may have hindered adsorption of xanthate, whereas the collector could be adsorbed on the copper sulphide minerals to promote their hydrophobicity. Development of the technology would not only result in reduced emissions of sulphur dioxide but would also solve the problem of pipelines becoming blocked by lime, resulting in considerable cost savings., The low-grade Iranian ore contains pyrite, which causes some problems in the flotation of chalcopyrite and other sulphide minerals. It was shown in experiments that selective flotation of the copper sulphides is possible when they interact with Acidithiobacillus ferrooxidans grown in the presence of either natural ferrous ion or sulphur. The bacteria did not adhere significantly to the chalcopyrite but could selectively adhere to the surface of pyrite, hindering its flotability and acting as a depressant. Cells strongly adsorbed on the pyrite surface may have hindered adsorption of xanthate, whereas the collector could be adsorbed on the copper sulphide minerals to promote their hydrophobicity. Development of the technology would not only result in reduced emissions of sulphur dioxide but would also solve the problem of pipelines becoming blocked by lime, resulting in considerable cost savings.

Studies have been undertaken to upgrade low grade celestite ore, containing 47.5% SrO, 9.3% CaO and less than 0.1% Ba, from the Iranian deposit. The aim was to produce a concentrate with a minimum of 95% celestite for conversion into carbonate. Various gravity separation methods were used and a combination of jig and shaking table or spiral concentrator showed sufficient potential for beneficiation of coarse particles. Flotation and Mozley multigravity separation were used to upgrade fine particles. Both methods produced promising results, but Mozley multigravity separation was selected because of its simplicity and environmental advantages., Studies have been undertaken to upgrade low grade celestite ore, containing 47.5% SrO, 9.3% CaO and less than 0.1% Ba, from the Iranian deposit. The aim was to produce a concentrate with a minimum of 95% celestite for conversion into carbonate. Various gravity separation methods were used and a combination of jig and shaking table or spiral concentrator showed sufficient potential for beneficiation of coarse particles. Flotation and Mozley multigravity separation were used to upgrade fine particles. Both methods produced promising results, but Mozley multigravity separation was selected because of its simplicity and environmental advantages.

The rougher circuit at the Miduk Cu concentrator, Iran, includes five flotation columns in parallel, each 12 m in height and 4 m in diameter. The mixing conditions were studied using residence time distribution data. A liquid radioactive tracer was used to trace the material reporting to tailings and concentrate, and external scintillation detectors were employed to record the tracer intensity without disturbing the flow pattern. The results showed that large and small tank-in-series and N perfect mixers in series were the best models for the flow patterns of liquid transferred to tailings and to concentrate, respectively. The ratio between the residence time of liquids and solids was 1.4:1. The solids content and grade profiles along the collection and froth zones of one of the columns were also measured. The results showed that, despite the presence of vertical baffles, mixing was close to well mixed conditions. Increasing the gas flow rate resulted in reduced mean residence times for liquid transferred to both tailing and concentrate streams and increased degree of mixing., The rougher circuit at the Miduk Cu concentrator, Iran, includes five flotation columns in parallel, each 12 m in height and 4 m in diameter. The mixing conditions were studied using residence time distribution data. A liquid radioactive tracer was used to trace the material reporting to tailings and concentrate, and external scintillation detectors were employed to record the tracer intensity without disturbing the flow pattern. The results showed that large and small tank-in-series and N perfect mixers in series were the best models for the flow patterns of liquid transferred to tailings and to concentrate, respectively. The ratio between the residence time of liquids and solids was 1.4:1. The solids content and grade profiles along the collection and froth zones of one of the columns were also measured. The results showed that, despite the presence of vertical baffles, mixing was close to well mixed conditions. Increasing the gas flow rate resulted in reduced mean residence times for liquid transferred to both tailing and concentrate streams and increased degree of mixing.

Cu-containing dust from furnaces at the Sarcheshmeh, Iran, complex was subjected to a sulphuric acid leaching process followed by bacterial leaching. Shaking-flask and bioreactor tests were conducted using a mixed culture of Acidithiobacilli and the effects of culture medium, pulp density and bacterial inoculation rate were investigated. Increasing the pulp density resulted in higher toxicity and shear stress, and substantially more microorganisms and a richer nutrient medium were required. The beneficial conditions in the agitated bioreactor led to marked promotion of metal dissolution rate in comparison with shaking flasks. Cu recoveries using shaking flasks and chemical leaching were 87% and 38%, respectively, after 22 days. Under the same condition, the maximum Cu recovery in the bioreactor was 91% within 6.5 days., Cu-containing dust from furnaces at the Sarcheshmeh, Iran, complex was subjected to a sulphuric acid leaching process followed by bacterial leaching. Shaking-flask and bioreactor tests were conducted using a mixed culture of Acidithiobacilli and the effects of culture medium, pulp density and bacterial inoculation rate were investigated. Increasing the pulp density resulted in higher toxicity and shear stress, and substantially more microorganisms and a richer nutrient medium were required. The beneficial conditions in the agitated bioreactor led to marked promotion of metal dissolution rate in comparison with shaking flasks. Cu recoveries using shaking flasks and chemical leaching were 87% and 38%, respectively, after 22 days. Under the same condition, the maximum Cu recovery in the bioreactor was 91% within 6.5 days.

The catalytic activity of five cultures of acidophilic bacteria for pyrite oxidation were studied for various pyrite pulp densities. These were Thiobacillus ferrooxidans DSM 581 as a mesophile, strain TSB as a moderate thermophile and Acidianus brierleyi DSN 1651, Sulfolobus acidocaldarius ATCC 33909nm, and strain L1 as extreme thermophiles. Optimum growth conditions for these were determined. The wild strain TSB, isolated from Iranian hot acidic springs and not previously used metallurgically, was found to the most effective and likely to be adaptable and to grow under leaching conditions, The catalytic activity of five cultures of acidophilic bacteria for pyrite oxidation were studied for various pyrite pulp densities. These were Thiobacillus ferrooxidans DSM 581 as a mesophile, strain TSB as a moderate thermophile and Acidianus brierleyi DSN 1651, Sulfolobus acidocaldarius ATCC 33909nm, and strain L1 as extreme thermophiles. Optimum growth conditions for these were determined. The wild strain TSB, isolated from Iranian hot acidic springs and not previously used metallurgically, was found to the most effective and likely to be adaptable and to grow under leaching conditions

An investigation was carried out into the use of Thiobacillus ferrooxidans bacteria in the selective flotation of Sarcheshmeh low-grade, pyrite-containing Cu sulphide ore. In the presence of Thiobacillus ferrooxidans and xanthate as collector pyrite was depressed while chalcopyrite and other sulphide minerals were unaffected. The pulp pH remained unchanged. The results showed that the surface chemical properties of pyrite and sulphide ores could be changed in the presence of the bacteria to achieve the desired effects in flotation. Recovery of pyrite in the presence of the bio-depressant was 50% lower. Recovery of chalcopyrite was not affected., An investigation was carried out into the use of Thiobacillus ferrooxidans bacteria in the selective flotation of Sarcheshmeh low-grade, pyrite-containing Cu sulphide ore. In the presence of Thiobacillus ferrooxidans and xanthate as collector pyrite was depressed while chalcopyrite and other sulphide minerals were unaffected. The pulp pH remained unchanged. The results showed that the surface chemical properties of pyrite and sulphide ores could be changed in the presence of the bacteria to achieve the desired effects in flotation. Recovery of pyrite in the presence of the bio-depressant was 50% lower. Recovery of chalcopyrite was not affected.

The relationship was investigated between collection zone rate constant and the gas dispersion parameters of bubble size, superficial gas velocity, gas hold-up and bubble surface area flux. Experiments were conducted in an industrial flotation column 4 m in diameter and 12 m high and a pilot column 0.1 m in diameter and 4 m high in the rougher circuit at the Miduk Cu concentrator in Iran. The results showed that the collection zone rate constant was not correlated solely with bubble size and superficial gas velocity, but was linearly dependent on gas hold-up and bubble surface area flux. The collection efficiency and floatability factor in the industrial columns were determined. The effect of process parameters on flotation kinetics decreased in the order superficial gas velocity, slurry % solids, frother dosage and frother type. Increasing the superficial gas velocity and frother dosage enhanced the flotation rate while an increase in slurry solids content reduced it., The relationship was investigated between collection zone rate constant and the gas dispersion parameters of bubble size, superficial gas velocity, gas hold-up and bubble surface area flux. Experiments were conducted in an industrial flotation column 4 m in diameter and 12 m high and a pilot column 0.1 m in diameter and 4 m high in the rougher circuit at the Miduk Cu concentrator in Iran. The results showed that the collection zone rate constant was not correlated solely with bubble size and superficial gas velocity, but was linearly dependent on gas hold-up and bubble surface area flux. The collection efficiency and floatability factor in the industrial columns were determined. The effect of process parameters on flotation kinetics decreased in the order superficial gas velocity, slurry % solids, frother dosage and frother type. Increasing the superficial gas velocity and frother dosage enhanced the flotation rate while an increase in slurry solids content reduced it.

Coal from Tabas in Iran contains fine, disseminated pyrite which is floated with the coal and reduces the quality of the final concentrate. Reagents such as sodium cyanide are typically added to depress pyrite. The desulphurisation of coal samples using conventional flotation with sodium cyanide was compared with results obtained using bioflotation in the presence of Acidithiobacillus ferrooxidans. The bacterial treatment reduced the pyrite flotation rate and improved the selectivity between coal and gangue. The bacteria were more successful in rendering the pyrite surface hydrophilic. The environmental benefits of using bacteria in place of toxic chemicals such as cyanide are discussed., Coal from Tabas in Iran contains fine, disseminated pyrite which is floated with the coal and reduces the quality of the final concentrate. Reagents such as sodium cyanide are typically added to depress pyrite. The desulphurisation of coal samples using conventional flotation with sodium cyanide was compared with results obtained using bioflotation in the presence of Acidithiobacillus ferrooxidans. The bacterial treatment reduced the pyrite flotation rate and improved the selectivity between coal and gangue. The bacteria were more successful in rendering the pyrite surface hydrophilic. The environmental benefits of using bacteria in place of toxic chemicals such as cyanide are discussed.

An axial dispersion model was used for the scale-up and design of a pilot-scale flotation column taking into account the collection rate constant and the froth recovery. A column 10 cm in diameter and 400 cm high was installed and tested in the rougher circuit at the Miduk Cu concentrator, Iran. The performance was shown to be better than the industrial column under the same operating conditions; this was attributed to the different bubble generation processes, mixing conditions and froth characteristics., An axial dispersion model was used for the scale-up and design of a pilot-scale flotation column taking into account the collection rate constant and the froth recovery. A column 10 cm in diameter and 400 cm high was installed and tested in the rougher circuit at the Miduk Cu concentrator, Iran. The performance was shown to be better than the industrial column under the same operating conditions; this was attributed to the different bubble generation processes, mixing conditions and froth characteristics.

The froth zone of a rougher column at the Miduk copper concentrator in Iran was studied. The solids and grade profiles along the froth zone indicated that most of the upgrading took place just above the interface where major loss of the bubble surface occurred. A considerable proportion of the feed water reported to the concentrate, particularly at higher gas velocities, indicating that the rougher columns represented a compromise between grade and recovery. The overall flotation rate constant increased nearly linearly with bubble surface area flux for shallow and intermediate froth depths but deviated from linearity at higher froth depths, indicating that mass transfer from the collection to the froth zone is rate-limiting at shallow froth depths and that transfer from the froth over the cell lip is rate-limiting at greater froth depths. Equations are presented showing the relationships between overall rate constant, froth depth and gas velocity; froth recovery and froth residence time; and overall rate constant, bubble surface area flux and slurry froth residence time., The froth zone of a rougher column at the Miduk copper concentrator in Iran was studied. The solids and grade profiles along the froth zone indicated that most of the upgrading took place just above the interface where major loss of the bubble surface occurred. A considerable proportion of the feed water reported to the concentrate, particularly at higher gas velocities, indicating that the rougher columns represented a compromise between grade and recovery. The overall flotation rate constant increased nearly linearly with bubble surface area flux for shallow and intermediate froth depths but deviated from linearity at higher froth depths, indicating that mass transfer from the collection to the froth zone is rate-limiting at shallow froth depths and that transfer from the froth over the cell lip is rate-limiting at greater froth depths. Equations are presented showing the relationships between overall rate constant, froth depth and gas velocity; froth recovery and froth residence time; and overall rate constant, bubble surface area flux and slurry froth residence time.

The bacterial leaching was investigated of Cu dust from the smelting furnaces at the Sarcheshmeh, Iran, Cu mine. Sulphuric acid leaching was performed prior to bacterial leaching and shaking flask experiments carried out using a mixed culture of thiobacilli. Cu recoveries from inoculated and control flasks using 5% pulp density were 87% and 38%, respectively, after 22 days., The bacterial leaching was investigated of Cu dust from the smelting furnaces at the Sarcheshmeh, Iran, Cu mine. Sulphuric acid leaching was performed prior to bacterial leaching and shaking flask experiments carried out using a mixed culture of thiobacilli. Cu recoveries from inoculated and control flasks using 5% pulp density were 87% and 38%, respectively, after 22 days.

The investigation showed that the selective flotation of sulphide copper minerals from pyrite is possible by interaction of the minerals with both ferrous- and sulphur-grown T. ferrooxidans bacteria, which promote surface chemical changes in the minerals. Depression of pyrite was 50% greater than in the absence of bacteria, with S-grown bacteria proving the more effective of the two types., The investigation showed that the selective flotation of sulphide copper minerals from pyrite is possible by interaction of the minerals with both ferrous- and sulphur-grown T. ferrooxidans bacteria, which promote surface chemical changes in the minerals. Depression of pyrite was 50% greater than in the absence of bacteria, with S-grown bacteria proving the more effective of the two types.

Zonous material is suitable (after appropriate classification and physical upgrading) for high quality ceramics, but preliminary bleaching tests indicate that brightness values could be significantly improved, suggesting that paper applications might also be possible. The presence of significant quantities of alunite in the Koshk material would almost certainly preclude its use in paper and even many ceramic applications. The Isyso material appears to be good kaolinitic clay, but the high content of iron and titanium-bearing minerals would appear to limit its potential use in markets such as papermaking, ceramics and other industries requiring a white product., Zonous material is suitable (after appropriate classification and physical upgrading) for high quality ceramics, but preliminary bleaching tests indicate that brightness values could be significantly improved, suggesting that paper applications might also be possible. The presence of significant quantities of alunite in the Koshk material would almost certainly preclude its use in paper and even many ceramic applications. The Isyso material appears to be good kaolinitic clay, but the high content of iron and titanium-bearing minerals would appear to limit its potential use in markets such as papermaking, ceramics and other industries requiring a white product.

In this investigation the biological leaching of aluminum by isolated fungi from low grade bauxite (<50 Al2O3.) was studied. X-ray diffraction investigation indicated that silicate and aluminosllicate minerals were major mineral composition. Wet chemical and electron disperse X-ray analysis showed the presence of aluminum, iron, silica and titanium. Biological leaching tests were carried out using indigenous specimen fungi, Aspergillus niger, Penicillium notatum. Savored Dextrose chloramphenicol Agar (SDA) was used as medium for the selected fungi. All microorganisms were tested for acid-production and leaching capabilities of aluminum from low grad bauxite. Leaching experiments were performed in 250-ml Erlenmeyer flasks at 28°C and at 150 rpm agitation under aseptic conditions. Pry heating of bauxite and its effect on leaching process was studied. Indigenous specimen fungi were the most efficient of the fungal cultures; 7080 mg of Al2O3/l was solubilized at 15 pulp density of bauxite. The metal content of leaching solution was determined by using wet chemical and atomic absorption spectrophotometer.