copper flotation free

the complete collection of copper beneficiation reagents | fote machinery

the complete collection of copper beneficiation reagents | fote machinery

In the flotation process of the copper mine, the use of flotation reagents to change the surface properties of the mineral is a flexible and effective way to control the flotation behavior. It is also an important reason why flotation can be widely used in mineral processing. This article mainly focuses on copper collectors, inhibitors, activators, foaming agents, ore-leaching bacteria, lixivium, extractants, etc.

Copper and sulfur in copper ore have strong collection properties, which is also conducive to improving the recovery of associated gold in copper sulphide ores. The flotation effect of refractory copper-sulfur ore containing secondary copper minerals is better than that with butyl xanthate, but its selectivity is worse.

As the excellent collector and foaming agent for non-ferrous metal ores, it has a special separation effect on the copper, lead, silver and activated zinc sulfide ores and refractory polymetallic ores.

It has stronger collection capacity than xanthates, especially for chalcopyrite. It has weaker collection capacity for pyrite, but better selectivity and faster flotation speed. Better separation effect than xanthate can be obtained by using it in the separation of copper-lead sulfide ore.

As the highly selective collector, it has very low solubility in water and high activity for flotation of copper, zinc, molybdenum and other sulfide ores, as well as precipitated copper, segregate copper, etc. It's often used in combination with water-soluble collectors to increase the efficacy, reduce dosage and improve selectivity.

DMDC: It has a strong collection capacity for copper and a weak collection capacity for pyrite and unactivated sphalerite. It can be used for copper and sulfur separation and its flotation index is higher than butyl xanthate.

Compared with the xanthate or aerofloat, it has higher selectivity and stability. It has a stronger collection effect on chalcopyrite and chalcocite, but a weaker collection ability on pyrite. The amount of pyrite inhibitor can be reduced during the flotation of copper sulfide.

Under the condition of alkalescence, it has good collecting ability and selectivity for chalcopyrite and other copper-bearing minerals, as well as strong collecting ability for associated precious metals such as gold and silver.

QF collector, containing thiocarbonyl functional groups, has strong collection capacity for natural gold, chalcopyrite and other minerals. Its ability to collect gold and copper is higher than that of low-grade xanthate and dithiocarbamate collectors.

PN405 has a strong selective collecting and foaming capacity for copper ore. By using this agent alone or with a small number of xanthate collectors, a better selection index can be obtained when floating the copper. It is also a high-efficiency collecting and foaming agent for copper-nickel sulfide ore to be used in conjunction with Y89 xanthate.

MOS-2 has strong new selective collecting ability for copper ore and weak collecting ability for pyrite. The separation of copper and sulfur can be realized and the dosages of collectors, lime and no. 2 oil can be reduced in lower alkaline medium by using it. Mos-2 collector also has a good foaming performance, so when using it as a collector, less or no foaming agent can be used.

It is a new class of ester collector for copper sulfide, which can preferentially collect copper in the rough selection stage with strong chemical adsorption on the surface of copper, and it is not easy to fall off.

It has good collecting performance and selectivity for copper sulfide, good selectivity for skarn copper ore with high secondary copper content, and can separate copper and sulfur in low alkaline medium.

It is a collector of copper sulfide ore, which has both foaming properties with rich and non-sticky foam, good selectivity, strong collecting property and fast flotation speed to improve concentrate grade. It has a wide PH range and can be added in stock solution.

It is a modified chalcophile chelating agent, which has no other hydration group except the groups that can form chelating compounds with copper, and can form stable hydrophobic polymers insoluble in water (or with very low solubility) with the surface of copper oxide.

It has a strong inhibitory effect on sulphide ores other than chalcopyrite. It can avoid the inhibitory effect on chalcopyrite when using too much sodium sulfide. It can be used in combination with sodium sulfite and zinc sulfate.

The combination of T-16 + zinc sulfate inhibitor can inhibit zinc, activate copper and lead, and eliminate the effect of slurry foam viscosity, which can effectively realize the flotation separation of copper-lead and zinc.

One of the development trends of mining is the application of bioleaching technology to recover important metals from various low-grade ores. Compared with traditional mineral processing technology, biological leaching technology has the characteristics of low cost, easy operation and low pollution.

The extractant can chemically react with the extract to form an extractable compound that can be dissolved in the organic phase, which is the most critical factor affecting the success of the extraction process.

In the flotation process of copper ore, the beneficiation reagent is an important factor that determines the flotation effect. It is one of the main research directions of mineral processing workers to explore a new copper flotation process and develop new cost-effective and environmentally friendly reagents to improve the utilization rate of copper resources.

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copper sulfide flotation

copper sulfide flotation

Copper, due to the present world demand and price, is of foremost interest to the mining industry. Many new properties are either in the process of being brought into production or are being given consideration. Copper minerals usually occur in low grade deposits and require concentration prior to smelting. The method and degree of concentration depends on smelter location and schedules, together with the nature of the ore deposit. Sulphide copper ores generally occur with pyrite, pyrrhotite, arsenopyrite and molybdenite, and with gold and silver. A complete copper-iron separation may not always be essential for the maximum economic recovery and often is tied to the distribution of the gold and silver values.

The above flowsheet is designed for the treatment by flotation of copper as chalcopyrite with gold and silver values. The ore, ranging from 60-65% silica, with pyrite, arsenopyrite, and calcite with 3 to 4% copper. This flowsheet, though simple, is adequate for tonnages of 100 to 500 tons or more per day, depending on the size of equipment selected. It can be readily expanded by duplicating units for increased tonnages. By minor circuit changes, it provides the flexibility to treat a range of ore conditions which are often encountered in any mining operation. Generally in these small plants the recovery of molybdenum is disregarded unless it is present in considerable amounts. Larger plants generally will incorporate a circuit for molybdenum recovery from the copper concentrate by flotation. Sub- A Flotation is standard for this service.

Crushing Section. The crushing section with two-stage reduction is suitable for smaller tonnages, depending on the ore characteristics. Three-stage reduction in either an open or closed circuit, with screens for the removal of fines can be employed where conditions warrant. The fines are removed by a grizzly or screen ahead of each reduction stage for higher efficiency and for reduced wear on crushing surfaces.

Feed control is essential to efficient grinding and helps reduce surges and fluctuations throughout the entire plant. The Ball Mill in closed circuit with a Spiral Classifier discharges the pulp at about 60% minus 200 mesh. The Ball Mill is equipped with a Spiral Screen on the discharge for removal of any tramp oversize, worn grinding balls, and wood chips from the circuit.

The pulp from the Conditioner is treated in a 10-cell Sub-A Flotation Machine and a 4-cell Sub-A Flotation machine. Sometimes conditioners are not provided; however, their use insures that reagents are thoroughly mixed into the pulp ahead of flotation. This gives a more uniform feed and effective use of reagents plus improved flotation conditions. The 10-cell Sub-A Flotation Machine is of the free-flow type. Weirs for the control of pulp level through the machine are provided at the fourth, eighth and tenth cells. This free-flow type provides ample volume for normal fluctuations in the feed rate without cell level adjustment. Sand relief ports help extend the long life of the molded rubber wearing parts.

The first eight cells produce a rougher concentrate while the last two cells act as scavengers. The concentrate or middling product from these two cells is returned by gravity back to the fifth cell. The rougher concentrate from the first eight cells is cleaned in two stages in the four-cell standard Sub-A Flotation Machine, of the cell-to-cell type. No pumps are needed for the return of these flotation products for cleaning. This feature in Sub-A Flotation Machines gives added flexibility by enabling the operator to change cleaning circuits readily, should conditions require. The tailings from the cleaner flotation section are pumped back to the ball mill for regrind. To control dilution a cone classifier is placed in this circuit with the coarse solids going to regrind and the overflow used as dilution in the mill and classifier. It is possible to eliminate this classification in some cases but control is less positive. A separate regrind section could be provided if the quantity of middling products were enough to make this section feasible.

The final cleaned flotation concentrate flows or is pumped to a Spiral Rake Thickener. A Adjustable Stroke Diaphragm Pump, mounted on the thickener superstructure, meters the thickened concentrate to the Disc Filter. The Thickeners are often used to store concentrates for filtration at fixed intervals. These units have heavy duty construction throughout, overload indicators and positive rake lifting features. The Diaphragm Pump is used for concentrate recirculation purposes during such periods.

Lime is added to the Ball Mill by a Cone Type Dry Reagent Feeder. Other reagents, such as cyanide, xanthate, and a frother are fed and controlled by No. 12A Wet Reagent Feeders to the classifier and to the conditioner ahead of flotation.

This flowsheet stresses simplicity without sacrifice of efficiency. The factors of flexibility are essential to meet changing ore and market conditions. The unit arrangement which can be expanded by sections for increased capacity is an important feature. The equipment indicated has been proven for long life and low maintenance, and to give superior results. The Sub-A Flotation Machines are designed for high capacity and with features of flexibility to handle fluctuating conditions with a minimum of operating attention. Low final tailings and high grade concentrate are assured through the selective action of the Sub-A in the roughing, cleaning, and recleaning circuits.

Large scale mining operations, of which the porphyry coppers are typical, must resort to concentration. This is necessary as the ores are generally low grade and require flotation to produce a concentrate acceptable to the smelters.

These large scale milling operations handling low grade ore must provide very careful planning in the design of their plant flowsheet and selection of equipment. Milling circuits must be as simple as possible and for large tonnages, as few as possible. It is for this reason grinding mills and flotation circuits arenow designed to handle these large tonnages at low cost.

Sub-A Flotation Machines are a basic part of large tonnage operations and their use assures maximum economic recovery. Particular emphasis has been placed on the design and operation of these machines for roughing, scavenging and cleaning. Mechanisms have been greatly simplified and molded rubber wearing parts are standard for maximum abrasion resistance.

Three stage crushing is illustrated in the flowsheet; however, it is possible and practical to eliminate the third stage by incorporating a rod mill in the grinding section. This is a very practical arrangement and often a necessity when handling wet, sticky ore. There is evidence that this combination of crushing and grinding results in lower costs for reducing large tonnages of ore to flotation size.

The flowsheet illustrates a typical grinding circuit with a rod mill in open circuit. Its discharge, usually all 14 mesh, goes to a classifier for removal of finished material. The classifier sands are ground in a ball mill in closed circuit with the same classifier. High speed rod milling with speeds up to 80% of critical has shown definite improvement in efficiency and grinding capacity. Proper selection of mill density and grinding charges are also factors of importance. Usually the rod mill is operated at lower density so it acts partially as its own classifier for retaining oversize for further size reduction.

Some conditioning of the pulp ahead of flotation is usually very beneficial and will result in more uniform and rapid flotation of a selective high grade concentrate. For this service the (patented) Super Agitator and Conditioner is standard. Reagents added at this point are thoroughly mixed and reacted with the pulp. Any tendency of the pulp to froth prematurely is readily overcome by the patented standpipe arrangement which also assures positive pulp circulation.

For large tonnage circuits normally encountered in many of the copper operations the open or free flow type Sub-A Super Rougher Flotation Machine is recommended. Intermediate cell weirs are eliminated and circulation of pulp through the impeller is fixed to provide the desired agitation and aeration for rougher flotation conditions. Machines are usually arranged with up to six cells being open or free-flow without intermediate weirs. Two or more machines are always provided in series. This allows adequate volume for absorbing surges and fluctuation in feed without cell adjustment. Mineral and middlings in the teeter or quiescent zone of the cell are gradually forced upward to the froth removal zone. Only the coarser material in the agitation zone passes through the impeller for further conditioning and bubble attachment.

In the flowsheet each circuit consists of 16 or 18 cells in 4 or 6 cell units. These Sub-A Super Rougher Flotation Free-Flow Machines are in series. All of the mechanisms are of the single impeller type and are completely supported from the superstructure to facilitate maintenance. All heavy hoods and castings are eliminated and the impeller-diffuser clearance is pre-set and accurately maintained throughout the long life of the heavy duty moulded rubber wearing parts. The last two cells are the super scavenger type giving veryintense agitation and aeration to float the last trace of recoverable mineral or middling for re-treatment.

Rougher flotation concentrates are cleaned in a standard Sub-A Flotation Machine with cell to cell pulp level control. This arrangement for upgrading concentrates is universal in its acceptance by the ore dressing industry. Two or more stages of cleaning in the same machine are accomplished without auxiliary pumps and ideal flotation conditions for producing high-grade concentrates are easily maintained.

Cleaner flotation tailings are returned to the head of the rougher flotation circuit for retreatment. In many milling circuits, particularly if coarse grinding is used, the cleaner tailings will contain middlings or mineral with attached particles of gangue. In these cases it is necessary to thicken or classify and regrind this fraction. Centrifugal classifiers are being very successfully applied for the classification step although they do take considerable power and require more maintenance than a thickener with its underflow going to a regrind circuit.

The flowsheet incorporates thickening for both the concentrates and tailings for water reclamation and tailings disposal purposes. A Adjustable Stroke Diaphragm Pump on the concentrate thickener assures absolute control of the volumes delivered to the Disc Filter. When the filter is down temporarily for bag changes the concentrates may be recirculated to the thickener by this same pulp.

Flexibility and simplicity are the two most important points to design into any large tonnage flotation operation. The arrangement shown is flexible and will permit addition of extra milling sections up to the limit of the designed capacity of the crushing plant. Sub-A Flotation Machines are designed specifically for high tonnage installations and have been proven for all types of applications. Rugged construction will give years of service at lowest possible cost. This flowsheet is readily adaptable for the treatment of other ores. Note particularly the location and use of Automatic Sampler.

Copper, one of our most important minerals, is found in many parts of the world. One of the major sources of Copper is the so-called porphyry ores such as the large deposits in the west and southwestern United States, Mexico, South America and Europe.

Porphyry ores, with copper occurring in the form of Chalcocite and Chalcopyrite are normally low in grade and the copper minerals must be concentrated before smelting. In this flowsheet using Sub-A Cells the emphasis is on maximum economic recoveryhigh concentrating efficiency together with a premium smelter feed with a low alumina and magnesia content in the flotation concentrate.

To obtain lowest tailings from this ore usually requires scavenging of rougher flotation tails. This is performed ideally by the Sub-A Super Rougher Flotation Machine which was specially developed for this duty. This machine has a double impeller and gives tremendous aeration. The flowsheet in this study is designed to get the maximum recovery from a large tonnage of porphyry copper ore.

The crushing section consists of three-stage ore reduction with either a grizzly or vibrating screen between each crushing stage. Removing fines before putting the ore through a crusher increases the efficiency of the crusher as it is then only working on material that must be reduced, and is not hampered by fines already reduced in size. Electromagnets and magnetic pulleys are used to remove tramp iron from the ore, the former to remove the iron near the surface and the magnetic pulley to remove the tramp iron close to the conveyor belt.

Porphyry copper ores usually are medium to medium hard and require grinding to about 65 mesh to economically liberate the copper minerals from the siliceous gangue. Sometimes a regrinding circuit is advantageous on the rougher concentrate and on the scavenger concentrate. This will liberate the mineral from the middling products and increase the recovery by putting those mineral particles into the concentrate. Rougher flotation may be accomplished at a relatively coarse grind and the subsequent regrind performed on a comparatively small tonnage.

Lime is usually added to the ball mill feed by a Dry Reagent Feeder. The frother and promoter are added in the classifier prior to flotation to realize the full effect of the reagent. Reagents can also be stage- added to the cells in the flotation circuit.

Standard Sub-A Flotation Machines are used for both the rougher and cleaner circuits, where their cell-to-cell principle gives both high recovery and a good grade of concentrate. The rougher concentration is accomplished in 6 or 8-cell flotation machines, with the concentrate from each goingto a separate bank for cleaning and re-cleaning. No. 30 Sub-A Flotation Machines are ideal for large tonnage operations, as each bank will handle from 1000 tons upward per day. Tails from the rougher circuit go to a scavenger circuit. Roughing, scavenging, cleaning and recleaning can be carried out in one bank of Sub-As. This is possible because of the distinctive gravity return of a product from any cell to any other cell of a bank without using pumps. In large installations, however, these steps are usually carried out in separate banks of cells. The scavenger flotation circuit consists of a 4-cell, Sub-A Super Rougher Flotation Machine with its super aeration. The concentrate from scavenger cells is returned to the head of the rougher cells and tails are sent to tailing pond. The new Sub-A Super Rougher Machine is designed especially to produce the lowest possible tailings in the mill circuit by scavenging off the last bit of recoverable and often difficult to float mineral. The Automatic Sampler is used on the flotation feed, concentrates and tailings to establish close mill control.

The flowsheet incorporates a thickener on the copper concentrates to thicken for optimum filtering. This also serves as a temporary storage space to accommodate operating requirements. The Adjustable-Stroke Diaphragm Pump on the thickener gives absolute control of volumes pumped to the filter. When the filter is shut down concentrates may be recirculated to the thickener by this same pump.

It is essential to have flexibility in any mill circuit, but particularly in large-tonnage operations such as this. Changing ore, changing market conditions and many other factors make this flexibility absolutely necessary. A slight change, easily made, in a flexible flowsheet may increase tonnage, improve recovery and lower grinding and reagent costs.

copper flotation

copper flotation

Although basic porphyry copper flotation and metallurgy has remained virtually the same for many years, the processing equipment as well as design of the mills has continually been improved to increase production while reducing operating and maintenance costs. Also, considerable attention is paid to automatic sensing devices and automatic controls in order to assure maximum metallurgy and production at all times. For simplicity in this study most of these controls are not shown.Many of the porphyry copper deposits contain molybdenite and some also contain lead and zinc minerals.

Even though these minerals occur in relatively small amounts they can often be economically recovered as by-products for the expense of mining, crushing, and grinding is absorbed in recovery of the copper.

Because the copper in this type of ore usually assays only plus or minus 1% copper, the porphyry copper operations must be relatively large in order to be commercial. The flowsheet in this study illustrates a typical 3,000 ton per day operation. In general most operations of this type have two or more parallel grinding and flotation circuits. For additional capacity, additional parallel circuits are installed.

The crushing section consists of two or three crushing stages with the second or third stages in either closed or open circuit with vibrating screens. Generally, size of the primary crusher is not determined by capacity but by the basic size of the mine run rock. The mine-run ore is normally relatively large as most of the porphyry mines are open pit.The crushing section illustrated is designed to handle the full tonnage in approximately 8 to 16 hours thus having reserve capacity in case of expansion.

Many mills store not only the coarse ore but also the fine ore in open stockpiles using ore as the side walls and drawing the live ore from the center. During prolonged periods of crusher maintenance the ore walls can be bulldozed over the ore feeders to provide an uninterrupted supply of ore for milling.

As it is shown in this study the or 1 crushed ore is fed to a rod mill operating in open circuit and discharging a product approximately minus 14-mesh. The discharge from this primary rod mill is equally distributed to two ball mills which are in closed circuit with SRL Rubber Lined Pumps and two or more cyclone classifiers. The rod mill and two ball mills are approximately the same size for simplified maintenance.

Porphyry copper ores, usually medium to medium hard, require grinding to about 65-mesh to economically liberate the copper minerals from the gangue. Although a clean rougher tailing can often be achieved at 65-mesh the copper mineral is not liberated sufficiently to make a high grade copper concentrate, thus some form of regrinding is necessary on the rougher flotation copper concentrate. It is not unusual to grind the rougher flotation concentrate to minus 200-mesh for more complete liberation of mineral from the gangue.

The cyclone overflow from each ball mill goes to a Pulp Distributor which distributes the pulp to two or more parallel banks of Flotation Cells. These distributors are designed so that one or more flotation banks can be shut down for maintenance or inspection and still maintain equal distribution of feed to the remaining banks.

In some cases it is beneficial to have conditioning before flotation, but this varies from one operation to another and it is not shown in this flowsheet. Ten or more Free-Flow Flotation Cells are used per bank and these cells are divided into groups of four or six cells with an intermediate step-down weir between groups. Free-Flow Flotation Cells are specified, as metallurgy is extremely good while both maintenance and operating expenses are traditionally low. One or more Free-Flow Mechanisms can be stopped for inspection or even replaced for maintenance without shutting down the bank of cells.

The concentrates from rougher flotation cells are sent directly to regrind. Often the grind is 200-mesh. After regrind is flotation cleaning. In some cases the concentrate from the first three or four rougher flotation cells can be sent directly to cleaning without regrinding.

After the rougher flotation concentrate is reground it is cleaned twice in additional Free-Flow Flotation Machines with the recleaned concentrate going to final concentrate filtration or, as the metallurgy dictates, to a copper-moly separation circuit.

The thickening and filtering is similar to other milling operations, however, as the porphyry copper installations are often in arid areas, the mill tailing is usually sent to a large thickener for water reclamation and solids go to the tailings dam.

Automatic controls are usually provided throughout modern plants to measure and control pulp flow, pH and density at various points in the circuit. Feed and density controls are relatively common and the newer installations are using automatic pulp level controls on flotation machines and pump sumps. Automation is also being applied to the crushing systems.

The use of continuous on stream X-ray analysis for almost instantaneous metallurgical results is not shown in thus study but warrants careful study for both new and existing mills. Automatic sampling of all principal pulp flows are essential for reliable control.

The flowsheet in this study illustrates the modern approach to porphyry copper treatment throughout the industry. Each plant will through necessity have somewhat different arrangements or methods for accomplishing the same thing and reliable ore test data are used in most every case to plan the flowsheet and design the mill.

In most plants engaged in the flotation of ores containing copper-bearing sulphide minerals with or without pyrite, pine oil is employed as a frother with one of the xanthates or aerofloat reagents or a combination of two or more of them as the promoter. Lime is nearly always used for maintaining the alkalinity of the circuit and depressing any pyrite present. The reagent consumption is normally within the following limits

While good results are often obtained with ethyl xanthate alone as a promoter, the addition of a small quantity of one of the higher xanthates is frequently found to improve the recovery of those minerals that are not readily floated by the lower xanthate, especially those that are tarnished or oxidized, but since the action of a higher xanthate is, as a rule, more powerful than that of the ethyl compound, it is usually best to add no more of the former reagent than is necessary to bring up the less readily floatable minerals, controlling flotation with the less powerful and more selective lower xanthate. Better results are obtained with some ores by replacing the higher xanthate with one of the dithiophosphates, flotation being controlled, as before, with ethyl xanthate. Sometimes a dithiophosphate can be effectively used without the xanthate, although the dual promotion method is more common. A rule of thumb system for the selection of these reagents cannot be laid down as the character of the minerals differs so widely in different ores ; the best combination can only be found by experiment.When aerofloat is employed alone as the promoter, the reagent mixture is somewhat different from that given above. A reliable average consumption is difficult to determine as the plants working on these lines are few in number, but the following is what would normally be expected.If this combination of reagents gives results equal to those obtainable with a xanthate mixture, its employment has these advantages over the latter method: The control of flotation is not so delicate as with xanthates, it has less tendency to bring up pyrite, and, if selectivity is not required, the circuit may be neutral or only slightly alkaline.

When the ore is free from pyrite, the function of the lime, whatever the reagent mixture, is to precipitate dissolved salts and to maintain the alkalinity of the pulp at the value which has been found to givethe best results ; soda ash is seldom employed for this purpose. When pyrite is present, lime performs the additional function of a depressor, the amount used being balanced against that of the promoterthat is, no more lime should be added than is required to prevent the bulk of the pyrite from floating, as any excess tends to depress the copper minerals, and no more of the promoter should be employed than is needed to give a profitable recovery of the valuable minerals in a concentrate of the desired grade, since any excess tends to bring up pyrite. In many cases a more effective method of depressing pyrite is to add a small quantity of sodium cyanidee.g., 0.05-0.10 lb. per tonin conjunction with lime, less of the latter reagent then being necessary than if it were used alone.

It is not often that a conditioning tank has to be installed ahead of the flotation section in the treatment of sulphide copper ores, as the grinding circuit usually provides suitable points for the introduction of the reagents. The normal practice is to put lime into the primary ball mills and to add xanthates at the last possible moment before flotation, while aerofloat and di-thio-phosphates are preferably introduced at some point in the grinding circuit, since they generally need an appreciable time of contact as compared with xanthates. There is no special place for the addition of pine oil, but care should be taken if it is put into the primary ball mills, as a slight excess may cause an undue amount of froth to form in the classifiers.

In a plant where the primary slime is by-passed round the grinding circuit, it is necessary to ensure that this portion of the pulp receives its correct proportion of and contact time with the reagents.

As regards flotation installations, the present tendency is to employ machines of the air-lift or Callow-Maclntosh rather than of the subaeration type. While two stages of cleaning (circuits 10 and 11) are sometimes essential to the production of a clean final concentrate, circuits 8 and 9 comprising a single stage of cleaning are probably the most widely used. Occasionally the primary machines can be run as rougher-cleaner cells (circuit No. 5), particularly when they are of the air-lift or subaeration type. This method, however, is not often employed, although its use is more common in the flotation of copper sulphide minerals than of any other class of ore ; a stage of cleaning is preferable as providing greater lattitude of control.

Two variations of normal procedure are worth notice. In one or two plants employing two-stage grinding, improved results have been obtained by separating the slime from the primary ball mill circuit and sending it direct to a special flotation section. This method is useful when the feed to the flotation plant contains an appreciable quantity of fines, which, due generally to oxidation through exposure, require different treatment from the unweathered part of the ore. Such fines are usuallyfriable and can be separated as slime from the primary grinding circuit without the inclusion of an undue proportion of unoxidized material, the bulk of which thus passes to the secondary grinding circuit and thence to its own division of the flotation plant.

The second variation consists of grinding the rougher concentrate before cleaning. The method is applicable to an ore in which the copper- bearing minerals are so intimately associated with pyrite that very fine grinding is necessary to liberate them completely. It is often possible, after grinding such an ore to a comparatively coarse mesh, to make a profitable recovery of the copper in a low-grade concentrate which does not represent too large a proportion, say 30% or less, of the total weightof the feed. The concentrate can then be reground and refloated with the production of a high-grade copper concentrate together with a low- grade pyritic tailing suitable for return to the roughing circuit. This method is likely to be less costly than one involving the fine grinding of the whole ore. No standard system can be given for handling the various products as their disposal depends so much on the occurrence of the minerals and the efficiency of the regrinding operations, but a typical flow sheet is illustrated in circuit No. 12 (Fig. 60). It is diagrammatic to the extent that the thickener and regrinding unit may receive its feed from several roughing machines and deliver its discharge to a number of cleaning cells. It is usual to dewater the rougher concentrate and return the water to the primary circuit for two reasons : First, to supply the regrinding mill with a thick enough pulp for efficient operation, and, secondly, as far as possible to prevent the reagents used in the roughing circuit from entering the cleaning section.

In normal practice a recovery of over 90% of the copper which is present as a sulphide is generally possible, whatever the flotation process or circuit employed. As regards the average grade of concentrate, no more can be said than that it depends on the class of the copper-bearing minerals present and their mode of occurrence and on the character of the gangue. It usually contains over 20% of copper, but a difficult chalcopyritic ore may yield a concentrate with less than that percentage, while it is theoretically possible to obtain one running over 75% should the mineral consist entirely of pure chalcocite.

The flotation of native copper ores is nearly always preceded by gravity concentration in jigs and tables not only because the combined process is more economical as regards costs, but also because the copper often occurs as large grains which flatten out during grinding and cannot be broken to a size small enough for flotation. The flow sheet depends on the mode of occurrence of the mineral. The tailings from some of the gravity concentration machines may be low enough in value to be discarded, but those products which still contain too much copper to be sent to waste are thickened and reground, should either operation be necessary, and then floated with pine oil and a xanthate or aerofloat reagent in a neutral or slightly alkaline circuit. The reagent consumption is approximately the same as that given for the treatment of copper- bearing sulphides. While a pine oil, lime, and ethyl xanthate mixture has proved satisfactory, better results have sometimes been obtained by the substitution of aerofloat and sodium di-ethyl-di-thio-phosphate, soda ash being used instead of lime on account of its gangue deflocculating properties. On the average 0-12 lb. per ton of aerofloat and 0.03 lb. of the di-thio-phosphate are substituted for 0.1 lb. of xanthate.

Since a high-grade concentrate is desired in order to keep smelting costs as low as possible, the circuit usually comprises two stages of cleaning. In most plants flotation is carried out in mechanically agitated machines.

The problem of the flotation of oxidized copper ores has not yet been solved. One or two special processes are in operation for the flotation of malachite and azurite, but none of them has more than a limited application; nor has any method been worked out on a large scale for the bulk flotation of mixed oxidized and sulphide copper minerals when the former are present in the ore in appreciable quantity.

minerals | free full-text | an improvement on selective separation by applying ultrasound to rougher and re-cleaner stages of copper flotation

minerals | free full-text | an improvement on selective separation by applying ultrasound to rougher and re-cleaner stages of copper flotation

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Hassanzadeh, A.; Sajjady, S.A.; Gholami, H.; Amini, S.; zkan, S.G. An Improvement on Selective Separation by Applying Ultrasound to Rougher and Re-Cleaner Stages of Copper Flotation. Minerals 2020, 10, 619. https://doi.org/10.3390/min10070619

Hassanzadeh A, Sajjady SA, Gholami H, Amini S, zkan SG. An Improvement on Selective Separation by Applying Ultrasound to Rougher and Re-Cleaner Stages of Copper Flotation. Minerals. 2020; 10(7):619. https://doi.org/10.3390/min10070619

Hassanzadeh, Ahmad, Sayed A. Sajjady, Hamed Gholami, Saeed Amini, and Safak G. zkan 2020. "An Improvement on Selective Separation by Applying Ultrasound to Rougher and Re-Cleaner Stages of Copper Flotation" Minerals 10, no. 7: 619. https://doi.org/10.3390/min10070619

minerals | free full-text | mineralogical prediction of flotation performance for a sediment-hosted coppercobalt sulphide ore | html

minerals | free full-text | mineralogical prediction of flotation performance for a sediment-hosted coppercobalt sulphide ore | html

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Feature Papers represent the most advanced research with significant potential for high impact in the field. Feature Papers are submitted upon individual invitation or recommendation by the scientific editors and undergo peer review prior to publication.

The Feature Paper can be either an original research article, a substantial novel research study that often involves several techniques or approaches, or a comprehensive review paper with concise and precise updates on the latest progress in the field that systematically reviews the most exciting advances in scientific literature. This type of paper provides an outlook on future directions of research or possible applications.

Editors Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to authors, or important in this field. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

development of copper recovery process from flotation tailings by a combined method of highpressure leachingsolvent extraction - sciencedirect

development of copper recovery process from flotation tailings by a combined method of highpressure leachingsolvent extraction - sciencedirect

A new flotation tailings treatment process was developed for efficient Cu recovery.An efficient Cu dissolution was achieved in an H2O media in presence of pyrite.The dissolution mechanism of CuFeS2 has been confirmed to be a multistage reaction.Fe was always co-dissolved with Cu following a linear relation of CFe=38.393CCu.Over 91% Cu was extracted from pregnant leach solutions by LIX-84I in Kerosene.

Sulfide copper mineral, typically Chalcopyrite (CuFeS2), is one of the most common minerals for producing metallic copper via the pyrometallurgical process. Generally, flotation tailings are produced as a byproduct of flotation and still consist of unrecovered copper. In addition, it is expected that more tailings will be produced in the coming years due to the increased exploration of lowgrade copper ores. Therefore, this research aims to develop a copper recovery process from flotation tailings using highpressure leaching (HPL) followed by solvent extraction. Over 94.4% copper was dissolved from the sample (CuFeS2 as main copper mineral) by HPL in a H2O media in the presence of pyrite, whereas the iron was codissolved with copper according to an equation given as CCu=38.40CFe. To avoid codissolved iron giving a negative effect on the subsequent process of electrowinning, solvent extraction was conducted on the pregnant leach solution for improving copper concentration. The result showed that 91.3% copper was recovered in a stripped solution and 98.6% iron was removed under the optimal extraction conditions. As a result, 86.2% of copper was recovered from the concentrate of flotation tailings by a proposed HPLsolvent extraction process.

recovery of copper from ammoniacal leachates by ion flotation | springerlink

recovery of copper from ammoniacal leachates by ion flotation | springerlink

Sulfidic copperleadzinc tailings can pose a significant environmental threat, ranging from generation of acid mine drainage (AMD) to dam failures. On the other hand, they can also be considered as low-grade ore resources for zinc and copper provided that novel economically feasible metal extraction and metal recovery techniques are developed. Due to the low metal concentrations in these resources, the leaching will generate dilute leachates from which metal recovery is a challenge. Ion flotation is a foam separation technique capable of recovering metal ions from dilute aqueous leachates. In this paper, ion flotation was applied to separate copper from ammoniacal leachates of microwave-roasted sulfidic tailings samples. The sulfidic tailings were first roasted at 550 C for 60 min, for the oxidation of sulfide minerals to more easily soluble sulfates using microwave-assisted irradiation as heating source. The microwave-roasted material was then leached with a mixture of ammonia and ammonium carbonate solutions. The optimum leaching efficiencies of zinc (86%) and copper (75%) were obtained under the following conditions: liquid-to-solid ratio = 10 mL g1, T = 90 C, [NH3 + NH4+] = 4 mol L1, NH3:NH4+ = 2:1, t = 5 h. From the generated pregnant leach solution, it was possible to selectively separate 85% of copper to the foam phase by ion flotation, with sodium dodecyl sulfate (SDS) surfactant, as colloidal copper(II) tetraamine dodecyl sulfate under the optimized conditions: [SDS]total = 5.85 mmol L1, [EtOH] = 0.5 % (v/v), ttotal = 5 h, flotation stages = 3. The zinc that remained in the solution after ion flotation was recovered by precipitation (95%) as basic zinc carbonate.

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The research leading to these results has received funding from the European Communitys Horizon 2020 Programme under Grant Agreement No. 812580 (MSCA- ETN SULTAN). This publication reflects only the authors view, exempting the Community from any liability. The authors thank Bart van Huffel (KU Leuven) for helping with the CHN analysis and Myriam Mertens (VITO) for the Rietveld refinement of the sulfidic tailings and the roasted material. The authors would like also to express their gratitude to Denita Avdibegovi (KU Leuven) and Sreko Bevandi (KU Leuven) for the fruitful scientific discussions.

Supplementary file1 The supporting information is available on the Springer Nature website and includes the elemental composition of sulfidic tailings, microwave-roasted material, and solid leaching residue (Table S1), the TGA analysis of sulfidic tailings sample (Fig. S1), the HSC simulation (Fig. S2), the XRD of the microwave-roasted material (Fig. S3), the metal concentration (mg L1) in the PLS (Tables S2S5), the residual metal concentration (mmol L1) of ion flotation experiments (Tables S6S8), a picture of the collected sublate (Fig. S4), the residual zinc concentration (mg L1) of the precipitation experiments (Table S9), the XRD of the precipitate (Fig. S5), and the metal concentration (mg L1) of the final solution (Table S10). (PDF 435 kb)

Xanthopoulos, P., Kalebi, D., Kamariah, N. et al. Recovery of Copper from Ammoniacal Leachates by Ion Flotation. J. Sustain. Metall. (2021). https://doi.org/10.1007/s40831-021-00363-1

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