GB2336794A

GB2336794A - Flotation device

Info

Publication number: GB2336794A
Application number: GB9809076A
Authority: GB
Inventors: Boris Koryukin
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-04-28
Filing date: 1998-04-28
Publication date: 1999-11-03
Anticipated expiration: 2018-04-28
Also published as: GB2336794B; GB9809076D0

Abstract

A column flotation device includes a casing 10, feed charging means 12, feed material introduction means operable to receive feed material from the charging means and introduce feed material at varying column depths, one or more aerators 16, and means 18,20 for discharging foam product and waste separately, wherein the charging means and/or one or more feed material introduction means is equipped with air introduction means 22,26 at an outflow zone thereof.

Description

2336794 FLOTATION MACHINE This invention relates to the processing of

mineral raw materials and particularly to the concentration of mineral products.

The concentration of minerals by counter flow flotation methods is known. In general, suitable flotation machines comprise a casing in the shape of a column, aerators, charging and discharging means to feed in raw materials and discharge products respectively. According to the principles of counter flow flotation, a flow of slime and water is established from top to bottom of the column and a flow of air bubbles from bottom to top. The air bubbles carry hydrophobic particles upwards and they are removed in the form of a foam product. Hydrophilic particles settle down and get removed by a discharging device at the base of the column.

A known column type flotation machine includes a conditioning member inside the column. A multi-row mixer is mounted inside the conditioning member and rods protrude horizontally from internal walls in the spaces between horizontal mixer rods of the multi-row mixer. The conditioning member is formed with a plurality of discharge holes opposite the lower row of mixer rods. Two g_ratings are located between the conditioning member and the aerator below it. A disadvantage of this type of flotation machine is the number of rotating and other moving parts which result in increased labour, power and wear costs.

Another known column type flotation machine comprises a system of coaxially arranged pipes. The upper ends of each pipe are in a hermetically sealed cylinder having a tangential branch pipe for the introduction of feed material

2 and the lower ends of each pipe are positioned within the column at different column depths.

Disadvantages of this type of flotation machine include the low quality of concentrate and insufficient extraction of the precious components into the concentrate. These problems result from the increased speed of outflow of materials from the coaxially located pipes caused by acceleration of these particles due to the decrease of the free cross- sectional area of the transient portion in the direction from the hermetically closed cylinder to the pipes.

This invention seeks to provide an improved flotation machine capable, for example, of producing a higher quality of concentrate and a greater yield of extraction of the precious components to the concentrate.

According to an aspect of the present invention there is provided a flotation machine including: a casing; charging means; feed material introduction means operable to receive feed material from the charging means and to introduce the feed material at varying column depths; one or more aerators; and means for receiving foam product and waste separately, wherein the charging means and/or one or more of the feed material introduction means is equipped with air introduction means at an outflow zone thereof.

According to another aspect of the present invention there is provided a flotation machine including a casing; charging means; feed material introduction means operable to receive feed material from the charging means and to introduce the feed material at varying column depths; one or more aerators; and means for receiving foam product and waste separately, wherein the charging means and/or one or more of the feed material introduction means is equipped with nozzles having a

3 free cross-sectional area which increases in a downstream direction.

Preferably, nozzles having compressed air ejectors are used to introduce the air to the charging means and/or each feed material introduction means.

In preferred embodiments, the nozzles are formed in the shape of truncated cones with downwardly facing bases. The nozzles are supplied with air from air supply lines 27. Preferably the feed material introduction means comprise coaxially arranged pipes having nozzles fastened in the outlet holes thereof. Deflector baffles are provided below the nozzles of the charging means and each pipe outlet. An arrangement of annular baffle plates of wedge shaped cross-section are located on internal surfaces of the casing at about the level of the ejectors.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing in which the sole Figure which shows a schematic view of a preferred flotation machine.

Referring to the Figure, the preferred flotation machine comprises a generally column shaped casing 1-0, a charging device 12 fed by a tangential branch feed tube 14, feed material introduction means comprising coaxially arranged pipes 24, a plurality of aerators 16, and a foam receiver 18. The machine is largely in steel, but any suitable material can be used.

The charging device 12 is fitted at its downstream end with a plurality of tapered nozzles 22 having the shape of truncated cones. Each nozzle 22 is equipped with a compressed air ejector 26 supplied by air supply line 27. Similar nozzles 4 and compressed air ejectors are fitted at the outlet ends of each pipe 24 of the feed material introduction means. Deflector baffles 28 are provided under the main charging device 12 and under each of the pipes 24. A further series of annular baffle plates 30, wedge-shaped in annular crosssection are provided on the internal walls of the casing 10 at depths substantially corresponding to the positions of the air ejectors 26.

In use, air 32 is supplied to the air supply lines 27 and the aerators 16. Pulp feed material is supplied to charging device 12 through the branch pipe 14. The charging device 12 classifies the feed particles according to size by using a centrifugal force generated due to rotation of the pulp by tangential feeding. The feed material then proceeds in a downstream direction to the first tapered nozzles 22 with an ordered particle size distribution. The material is then passed to the main column via the coaxial pine arrangement 24 and subsequently to further tapered nozzles 22 provided at outflow zones thereof. Within the main column, four aerators 16 provide bubbles for a controlled flotation process. Hydrophobic minerals from broken ore become attached to air bubbles in the water and are carried upwards to form a foam. As the foam product accumulates, it flows over the upper peripheral portion of the foam receiver 18 and is removed by flowing through outlet 34. Hydrophilic minerals, slime and water continue downwards under the action of gravity and are discharged at the base of the column through discharge pipe 20.

The c.oaxially arranged feed pipes 24 of the feed material introduction means enable material to be evenly distributed by size and charged at different depth zones of the column. Larger sized feed material is introduced closer to the foam layer; this speeds up the flotation of large particles and increases the volume of their extraction. Smaller particles go into deeper zones of the column; the feeding of the fine grain material to deeper zones of the column increases the probability of liberating gases dissolving the water on hydrophobic or hydrophilic particles. It also contributes to the selectivity of the flotation separation of fine particles. In this way, the volume of the zone in which concentration and cleaning occurs is maximised. The manner in which mineralised bubbles go to the overflow lip is also more efficient. Charging the pulp via discretely separate input flows reduces significantly the turbulence at the point of the feed supply so that conditions for mineralisation and air bubble attachment are optimised.

The increase of free cross-sectional area of the nozzles 22 in a downstream direction reduces a vertical component of the velocity of the particles during the movement of the pulp. Reduced speed of outflow from the charging device 12 improves the conditions for the attachment of hydrophobic particles to air bubbles and increases extraction to the foam product. Compressed air supplied to the zones of outflow of the particles from the charging device 12 and pines 24 by ejectors 26 destroys association products of different minerals which are formed in the pulp, part-'--ularly when treating it with flotation agents. Hydrophobic particles released during the destruction of association products, which are similar to aggregations, are brought out to the foam product and hydrophilic particles to the chamber product. This inevitably leads to increased extraction efficiency of precious components and to the improvement of quality of overall product..

The taper angle and diameter of the nozzle inlet hole depends on the granularmetric composition of the feed material and different parameters will be selected depending, for example, 6 on the raw material being used and the position of the nozzles within the column. For applications in which small particle sizes predominate, the diameter of the nozzle inlet hole of a nozzle for the central pipe which passes the feed material into the casing is increased and the taper angle is decreased. The reverse applies where larger particle sizes predominate.

Impacts and frictional contact of feed material and mineralised bubbles with the deflector baffles and annular baffle plates enhances the process by virtue of a refining effect. The annular baffle plates are located on the internal walls of the casing at the level of the ejectors, so that the high levels of movement of the material in this zone due to the ejection of compressed air is maximised.

Flotation agents can be employed to increase or decrease the hydrophoby of some minerals. Such an approach allows the separation of the concentrate and tailings in the mineral mixture. Typical flotation agents include, for example, xanthates, which are salts of xanthic acid obtained from reactions between alcohols with carbon disulphide in the presence of base, preferably below 10 OC. Preferably one of potassium hydroxide and sodium hydroxide is chosen as the base and any suitable alcohol can be chosen zo provide of the main carbon chain. For example, the formula of potassium butylxanthate is C4H9OCSSK.

In modified embodiments, the configuration of column components may be varied considerably. For example, in one modified embodiment the air supply lines for the compressed air ejectors and/or aerators may be arranged differently or supplied by a common supply line. In another modified embodiment, the charging means employs different particle size classification means.

I 1 1 7 In another modified version, feed material conditioning/pretreatment means are incorporated with or precede the charging means. The arrangement of pipes constituting the feed material introduction means need not be limited to that disclosed. For example, one or more of the pipes may extend deeper into the column.

In other modified versions, different numbers and arrangements of aerators are provided in the lower region of the column. Such aerators may be of differing shapes or consist of more than one component. In some applications it is useful to provide one or more grating above the or each aerator as is known in the art.

Two examples of applications in which the efficiency of mineral extraction was improved considerably follow:

EXAMPLE 1

Final tailings of concentration of copper ore of Almalik deposit (Uzbekistan) were floated in the preferred apparatus and in a known alternative apparatus with each apparatus operating in continuous duty.

TABLE 1

Column-type Content of copper, % Extraction of flotation machine copper to foam 1 product, % Final Tailings (feed) Foam Producz Known 0.06 0.38 35 Preferred 0.06 0.80 78 As can be seen from table 1, the use of the preferred machine led to an increase of the copper content in the foam product 8 of the order 2.1 times and to an increase in the extraction of copper to the foam product by about 43%. Return of the foam product to the flotation head in which the content of copper is twice as high as in the initial ore corresponds to a saving of in the region of 300,000 US dollars in the processing of one million tonnes of final tailings.

EXAMPLE 2

Ore of Volkovski deposit (Ural) was float processed in known and preferred apparatus. TABLE 2 Column-type Content of copper, % Extraction of copper to flotation machine copper concentrate, % Ore (feed) Copper concentrate Known 0.62 17.13 79.33 Preferred 0.62 21.55 80.57 As can be seen from table 2, using the preferred flotation machine leads to an increased copper level in the concentrate of 4.2%, corresponding to an increase in the extraction of copper to the copper concentrate of about 1.24% (absolute). This would afford an economic saving of in the region of 18,000 US dollars in the processing of one million tonnes of ore at the expense of only extraction of ore.

9

Claims

1. A flotation machine including a casing; charging means; feed material introduction means operable to receive feed material from the charging means and to introduce feed material at varying column depths; one or more aerators; and means for receiving foam product and waste separately, wherein the charging means and/or one or more feed material introduction means is equipped with air introduction means by an outflow zone thereof. -

2. A flotation machine as in claim 1, wherein the or each air introduction means includes a nozzle equipped with compressed air ejection means.

3. A flotation machine as in claim 1 or 2, wherein each nozzle has a shape such that the free cross-sectioned area increases in a downstream direction.

4. A flotation machine as in claim 3, wherein each nozzle is formed substantially in the shape of a truncated cone or polyhedron-based pyramid, the base facing in a downstream direction.

5. A flotation machine as in any preceding claim, including means operable to distribute the feed material according to particle size before it enters the feed material introduction means.

6. A flotation machine as in any preceding claim, wherein the feed material introduction means comprises an arrangement of coaxially arranged pipes extending to various depths within the column.

7. A flotation machine as in claim 6, wherein nozzles are fitted at outlet zones of the charging means and each of the coaxial pipes.

8. A flotation machine as in any preceding claim, comprising detector baffles positioned below the outflow zones of the charging means or one or more of the coaxially arranged pipes.

9. A flotation machine as in any preceding claim, comprising one or more baffle plates provided within the casing at substantially the same level as the air introduction means.

10. A flotation machine as in claim 9, wherein approximately annular baffle plates, substantially wedge shaped in annular cross-section, are provided on the internal walls of the casing at depths substantially corresponding to those of the air ejectors.

11. A flotation machine including a casing; charging means; feed material introduction means operable to receive feed material from the charging means and to introduce the feed material at varying column depths; one or more aerators; and means for receiving foam product and waste separately, wherein the charging means and/or one or more of the feed material introduction means is equipped with nozzles having a free cross-sectional area which increases in a downstream direction.

12. A flotation machine substantially as described herein with reference to the accompanying drawing.