Flotation

Timed Flotation Test & Cumulative Grade Recovery Curve

grade-recovery-over-timed-flotationApart from conducting a rate test in the correct manner, it’s important to collect the right number of concentrates and at the right times; doing this will ensure that the data you generate maximizes your analysis of flotation response. To properly define the relationship between recovery and time, you need a minimum of four concentrates and four data points on the graph. flotation_recovery_over_timeThe timing of these concentrates is critical to ensure that the three major characterizing aspects of the recovery time curve are defined accurately. These aspects are the initial slope of the curve; the determination of fast floating rate is dependent on the accuracy of the slope. fast_floating_minerals_beginning_flotation_testFor this reason the first concentrate must be collected within two minutes; two minutes is the maximum time allowed. If concentrate is collected after this, calculated fast floating rate is less than its true value. slow_floating_mineral_grade_recovery_curve_timed_flotationThe second aspect is the slope of the curve at the end of the test; this determines the slow floating rate. ….Read more

Mineralogy & Flotation: Floatability VS Selectivity Test Assessment

flotation_1Mineralogy is the driving force behind flotation performance. A flotation batch and rate test measures this as mass pull recovery and concentrate grade. The real data from a rate test can be processed to determine the flotation kinetics of metal, mineral and gangue. flotation_rate_determination_testWhat we cover here is what are kinetics and what do they mean. Special attention is paid to the definition of floatable gangue. How flotation kinetics are used to understand and optimized flotation performance is covered in the next series. Two other articles describe how a rate test is conducted and what concentrate collection times should be used. A laboratory batch test or measurements done a bank of pilots or production scale plant cells generates a recovery grade and concentrate mass profiled with time. determine_mineral_flotation_kinetic_speed_rateThese profiles describe the flotation response and performance of the ore under whatever conditions are in effect at the time. In 1961 Kelsall developed a first order two component equation to fit these profiles. Flotation performance is described in terms of Fast and Slow components; each has a fraction ….Read more

Froth Flotation Applications

Unusual Applications Of The Flotation Process: In the mineral industry flotation is often defined as a physicochemical process that has the capability of separating two or more finely divided minerals from each other. In the usual concept of flotation all three forms of matter are involved and many of the physical and chemical properties of gases, liquids and solids can influence the process.

Examples of simple flotation operations might include the flotation of galena (PbS) from limestone or molybdenite (MoS2) from quartz. Progressing to more difficult separations would include mention of fluorspar, barite, galena, and quartz separations, the separation of metal- silicate minerals and the newly developed flotation processes for the selective recovery of beryllium minerals from a host of gangue minerals.

The reader of this paper should not completely accept any of the common definitions of flotation of unusual separations which now appear possible by proper application of froth flotation, foam flotation, skin flotation or agglomeration flotation. Some of the more unusual applications of flotation from solutions (even gold from sea water), selective separation of micro-organisms, selective separation of colloidal particles, and the flotation treatment of a host of organic and inorganic industrial wastes to concentrate various components.

This more liberalized concept of ….Read more

Flotation Kinetics: Mass & Water Recovery VS Entrainment & Mineralogy

flotation_1

This covers the recovery of entrained solids with water and the relationship between mineralogy and flotation performance; both are described in terms of flotation kinetics. The starting points for the relationship between mass and water recovery other products of a flotation rate test. flotation_entrainmentIn addition to concentrate mass, metal or mineral and floatable gangue. If the mass of water in each concentrate has been measured, then a fourth set of kinetics can be added which defines water recovery. This is useful if dealing with ultra-fine material or silicate gangue which has been recovered mainly by entrainment by water carry over to concentrate rather than being recovered by true flotation. how_frother_affect_flotation_entrainmentKnowing the kinetics of water recovery is also useful as one means of classifying frothers. The graph shows the relationship between mass and water recovery for PGM ores in colours other than yellow and twenty two variability samples for a nickel ore in yellow.pgm_flotation_entrainment_and_mineralogy

For reference, profiles for different silica size fractions from research conducted by Zheng ….Read more

Grind Size & Liberation for Optimum Flotation Recovery

Here is a trick for knowing if your flotation feed grind size is fine enough to achieve adequate mineral liberation without doing a full mineralogy study.

  • If your key mineral is sufficiently liberated, it should float and be recovered in the first few minutes in an initial %mass that stabilizes quickly
    = the green curve.
  • If, your valuable minerals are still badly locked, the longer you float, the more %mass you pull, the more your recovery increases
    = the red curve.

Sadly, I have seen unsavvy “metallurgist” do recovery VS flotation time tests only to falsely conclude they needed more flotation time to get a higher metal recovery. Selective flotation is allowed by a minimum liberation level in which you maximize metal recovery in a minimum mass. Recognizing the partners can save you much needless pain.

Now I do not advocate unnecessary grinding, but you need what you need.  I have seen some misguided mineral processing souls claim you could compensate grind (purposely under design the primary circuit) with more flotation time/capacity.

how-grind-size-liberation-affects-flotation-recoveryHow to Improve Flotation Recovery

Flotation Circuits Diagrams

Since several types of flotation circuits can generally be employed in conjunction with the various processes for the flotation of different classes of minerals, an outline of the standard circuits in common use is best given before the processes to which they are applicable are described. The flow sheets illustrating them are diagrammatic, but, in cases where the circuit includes two or more machines, the latter are shown in their approximate relative positions. The diagrams must not, however, be considered to represent exact plant layouts; any standardised arrangement will usually need a certain amount of alteration in minor details to suit a particular ore, not only to meet the requirements of the flotation process but also to conform to the design of the plant as a whole.

flotation circuit diagram

Flotation Circuits for Mechanically Agitated Cells

The simplest method of single-stage flotation with a machine of the mechanically agitated type is shown diagrammatically in Fig. 48. A finished concentrate

flotation-circuit-2

is taken off the first few cells and the remainder are run as scavengers, the froth from them being returned to the head of the machine through a middling ….Read more

Silver Gold Recovery Flotation Process

The ores from which silver and gold are recoverable by flotation divide themselves naturally into two general processing classes:

  1. ores in which the valuable minerals are those of the base metals, the precious metals being incidental constituents, and
  2. ores in which the gold and silver are of primary importance, the base-metal minerals, if present, being of little or no value.

The first class includes copper, lead, lead-zinc, copper-zinc, and copper-lead-zinc ores. Both gold and silver may be present, the gold values being usually associated with chalcopyrite and pyrite, and the silver with galena and tetrahedrite. Flotation follows ordinary standard methods, modified as may be necessary to bring up the precious metals in the concentrates where they will be of most value. Thus, in a lead-zinc ore, silver is more valuable in the lead than in the zinc concentrate. Similarly, in a copper or lead ore carrying gold associated with pyrite, it might be profitable to make an iron concentrate containing the gold. If the gold and silver can only be brought up in the desired concentrate by contaminating it with unwanted mineral, the mode of procedure must be determined by the economics of the case. Supposing, for example, that the recovery of ….Read more

Compare Flotation Machines Types

In the 1950s, the opinion was often expressed that the mechanically-agitated machine forms the best rougher and a pneumatic machine the best cleaner, the reason being that the former type has come to be regarded as one that yields a heavily-mineralized froth, which, though giving a good recovery of the minerals, is likely to be of low grade because of the presence of gangue particles mechanically trapped between the closely packed bubbles, whilst in the pneumatic cell the froth is generally deeper and more open with less heavily mineralized bubbles, a condition which provides more opportunity for the gangue to drop out. Such a statement, however, is scarcely true of modern practice, since the design of flotation machines has been improved so much in recent years that any one of them, in conjunction with efficient conditioning, can be run to give almost any required type of froth.Mineral Separation

Machines of the mechanically-agitated type are generally chosen for the flotation of ores which cannot be readily conditioned by chemical reagents and need prolonged agitation, sometimes with the addition of heavy collecting oils, in order to render them floatable. On account of their wide range of adjustment they ….Read more

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