FI75280B - KOLONNFLOTATIONSFOERFARANDE OCH -ANORDNING. - Google Patents

Abstract

The froth flotation device includes a flotation column partially filled with a packing which defines a large number of small flow passages extending in a circuitous pattern between the upper and lower portions of the column. A conditioned aqueous pulp of a mineral ore, such as iron ore. is introduced into the midzone of the column. A pressurized inert gas, such as air, is introduced into the bottom of the column and is forced upwardly through the flow passages in the packing. As the air flows upwardly through these flow passages, it is broken into fine bubbles which intimately contact the floatable particles (e.g., iron oxide) in the aqueous pulp and forms a froth concentrate or float fraction which overflows from the top of the column. Wash water is introduced into the top of the column and flows through the flow passages in the packing countercurrently to the float fraction to scrub entrained non-floatable particles (e.g., gangue) from the froth concentrate. A tailing fraction containing the non-floatable particles is withdrawn from the bottom of the column.

Description

75280

The present invention relates to flotation, and more particularly to a method for enriching a foamable material by flotation in an aqueous slurry comprising a mixture of floating and non-floating particles, and an apparatus for carrying out the method, the apparatus comprising a tubular flotation column comprising a top and a bottom; slurry feed means for introducing an aqueous slurry into the column at a point between the top and bottom; means for introducing wash water into the top of the column for downward flow; means for introducing a pressurized inert gas into the bottom of the column for upward flow; means for removing the floating portion of the aqueous slurry containing floating particles from the top of the column; and means for removing the waste portion of the aqueous slurry containing non-floating hfukase from the bottom of the column. 20 Flotation has been used for years to enrich many minerals and to separate many other materials. Flotation involves the separation of particles in a liquid slurry based on differences in hydrophobicity. The sludge is aerated by bringing in a lot of 25 very small air bubbles. Air bubbles tend to adhere to floating (hydrophobic) particles and cause those particles to rise to the surface as a flotation product that overflows from the flotation device, leaving non-floating (hydrophilic) particles behind.

50 An article entitled "Flotation Machines" in the publication

Mining Magazine, January 1382, page 35, describes several different types of flotation equipment and methods used to enrich minerals. In the so-called column flotation, a homogeneous slurry is introduced in the middle region of a relatively long column and compressed air is introduced through an air distribution plate at the bottom of the column. The portion containing foamable particles, usually valuable mineral particles, flows over the top of the column and the portion containing non-foaming particles, usually wreckage, is removed from the bottom of the column by gravity or pump. Examples of prior column flotation equipment and methods have been reported in Canadian Patents 680,576 5 and 694.54-7, Canadian Chemical Processing, February 1965, pages 55-58, and E&MJ, Volume .66 No. 1, pages 76-78.83.

The air distribution plates in the flotation column tend to clog, especially if a descaler is used, causing an uneven distribution of air through the slurry.

Similarly, the small air bubbles generated at the bottom of the column tend to increase as they rise toward the top due to a change in static pressure inside the column, resulting in a reduced surface contact between the air and the particles. Various attempts have been made by Konia to alleviate this problem, including the use of hydrophobic materials and the introduction of air as a fine dispersion in water instead of the use of an air distribution plate. The latter company is disclosed in U.S. Patent 3,371,779.

It is an object of the present invention to provide an economical flotation method and apparatus which overcomes the disadvantages of the known types.

The invention provides a method of enriching a foamable material by flotation in an aqueous slurry comprising a mixture of floating and non-floating particles, characterized in that the method comprises the steps of providing a generally tubular flotation column comprising a top and bottom and at least partially filled with packing means. , defining a plurality of flow channels circulating between the top and bottom of the column; preparing an aqueous slurry for flotation separation of the particles therein; introducing the resulting slurry into the column at a point between the top and bottom for flow through the flow passages of the packing means; introducing wash water into the top of the column for downward flow through the flow passages of the packing means; introducing a pressurized, inert gas into the bottom of the column

II

3 75280 Filling means for upward flow through the flow passages, wherein the gas is broken up into fine bubbles which closely contact the particles of liquid slurry in the flow passages of the filling means; removing the floated portion of the liquid slurry containing floating particles from the top of the column; and removing the aqueous slurry from the bottom of the column containing unauthorized particles.

The device according to the present invention is characterized in that the filling means are arranged in a column between the top and the bottom and define a large number of small flow channels which meander between the top and the bottom and that the gas flows upwards through the flow channels and is broken into fine bubbles. which closely contact the liquid slurry particles in the flow channels.

An aqueous slurry containing a mixture of floating and non-floating particles is introduced into the column. The inert gas, preferably air, is broken up into fine bubbles as it is forced upwards through the flow channels of the filling means. The float bubbles are in close contact with the floating particles and form a foam concentrate or floating portion that contains the floating particles and flows over the top of the column. The wash water flowing through the flow-through flow channels upstream of the floating portion removes entrained non-floating particles from the floating portion and the waste portion containing the non-floating particles is removed from the bottom of the column.

In one embodiment, the filling means comprise a plurality of plates arranged vertically at certain distances from each other and spacer means for placing the plates laterally spaced apart from each other to define a plurality of small flow channels between adjacent plates. The spacer means may comprise rows of corrugations in each plate 35, preferably running obliquely to the horizontal.

In one embodiment, separate vertically adjacent plate compartments are provided. The web compartments are preferably oriented so that in each of said compartments the vertical planes of the plates are at an angle to the vertical planes of the plates of the adjacent compartment.

The use of filling means is advantageous because it li-5 adjusts the air-particle contact, eliminates the need for an air distribution plate which tends to clog during use and thus allows efficient operation with a minimum number of flotation steps and therefore uses a minimum amount of water and energy.

An embodiment of the invention is now described with reference to the accompanying schematic drawings, which are forged or for example.

Figure 1 is a schematic representation of a flotation column.

Figure 2 is an exploded, perspective view of section 15 corrugated sheets forming a packing compartment for the column shown in Figure 1.

The column flotation apparatus and method described can be used to separate a large number of materials with a wide particle size. It is very useful for separating valuable 20 mineral parts from wreckage in finely ground ores, such as low-grade, oxidized Taconite ores from the Ylöjärvi area. The device is described in connection with this application.

The flotation device 10 comprises a tubular column 12, 25 having a top H and a bottom 16, a slurry inlet 18 for introducing a uniform aqueous sludge or slurry of oxidized Taconite ore into the column at an intermediate point, a water inlet 20 for introducing scrubbing water into the column 12, and a gas inlet 22 30 as for introducing air into the lower part 16 of the column 12.

The column 12 may be generally vertical, as shown in Figure 1, or inclined at an angle to the vertical. The column 12 is partially filled with a filler 24 which defines a large number of small flow passages which pass between the upper part 14 and the lower part 16 in a circulating or tortuous manner.

The wash water introduced into the top of the column 12 through the water inlet 20 flows downwards through these flow channels *

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5,75280

The compressed air introduced into the lower part 16 of the column .12 through the gas inlet 22 is forced upwards through these flow channels, countercurrent to the wash water and part of the liquid slurry settles through these flow channels.

5 As the air passes upward through these flow channels, it is broken up into fine bubbles of relatively uniform size. The ascending bubbles are in intimate contact with the particles of the aqueous slurry within the flow channels of the filler 24 to provide a foam concentrate or chelating portion containing primarily floating particles and a smaller amount of substantially non-floating particles entrained in the foam. Air bubbles carry the foam concentrate 25 upwards to the foam compartment 26 at the top of the column 12. The foam concentrate 25 is removed from the foam chamber 26 by draining it through an outlet 28.

The wash water descending through the flow channels in the filling causes the iron-borne non-floating particles to separate from the foam concentrate and fall (i.e., sink) under the influence of gravity through these flow channels.

Since the wash water can be introduced into the column 12 in any conventional manner, it is most preferable to introduce it into the foam chamber 26 and above the upper surface of the foam concentrate 25 through a spray nozzle 32 centrally located at the top of the column. The spray pen 32 distributes many water jets over the foam in the foam vats 26, thus ensuring more even contact of the wash water with the non-floating particles in the foam concentrate 25 and thus a more even distribution of the wash water through the flow channels 30 in the filler 24. The waste portion 33, which contains the non-floating particles in the aqueous slurry, collects in the waste chamber 32 at the bottom of the column 12 and is removed therefrom through the outlet 34. Although not particularly accurate, the waste chamber 32 is preferably conical in shape, as shown in Figure 1, to assist in the removal of the waste portion. The waste section is preferably discharged through the outlet 34 by a conventional adjustable flow pump 36.

Since the column 12 can have different cross-sectional shapes, it has a square cross-section in the special structure described. The cross-sectional shapes and length of the column 12 are adjusted depending on the type of aqueous slurry to be treated, the special type of packing used, the desired throughput, and other variables familiar to those skilled in the art.

The packing 24 can take many different forms, which are capable of providing a substantially closed flow space and defining a large number of flow channels that rotate or meander between the top and bottom of the column 12. These flow channels cause the air bubbles to rupture and coalesce into fine bubbles of relatively uniform size, maximizing close surface contact with the floating particles. A suitable padding 15 comprises conventional padding materials used in padding pieces in a washing storm for vapor-liquid delivery methods, such as Raschig rings, Berlin saddle, separation rings and the like.

In the preferred embodiment described, the filler 24 is formed of a plurality of vertically extending plates 40 from a plurality of compartments 38a-38f. Each compartment comprises a plurality of plates 40 and spacer means for laterally spacing the plates 40 to define a plurality of relatively small flow channels between adjacent plates 40. In the special construction shown in Fig. 25, such spacer means comprise evenly spaced rows of corrugations 42 in each plate 40. The corrugations 42 preferably run diagonally, i.e. at an angle of approximately 45 ° to the horizontal, in order to omit vertical flow channels 30 of essential length. The angular orientation of the corrugations can be varied to control the flow through the flow channels. For example, this flow can be increased by increasing the angle of the alosts 42 with respect to the horizontal.

In order to further increase the rotation or meandering of the defined flow channels between the adjacent plates 40, the corrugations 42 of the alternating plates 40 preferably extend in a transverse direction, as illustrated in Figure 2.

The corrugations of one plate thus pass at an angle to the corrugations of the next 7 75280 plates. Adjacent compartments are also positioned so that the vertical planes of the plates of one compartment are at an angle (e.g., about 90 °) to the vertical planes of the plates of the adjacent compartment. According to Figure 1, the vertical planes of the plates 40 in compartments 38a, 38c and 38e run perpendicular to the side plane and the vertical planes of the plates of compartments 38b, 38d and 3Sf run parallel to the side plane.

The packing compartments 38c and 38d in the vicinity of the slurry inlet 38 are preferably spaced apart to provide a substantially free feed compartment or chamber 44. The packing compartments 38a, 38b and 38c above the feed chamber 44 form a column 12 below the primary purge compartment and the feed chamber 44. The filling compartments 38d, 38e and 38f form a flushing compartment in which the floating particles are separated from the settling waste.

In typical operation, iron ore, such as oxidized taconite, is ground to a particle size suitable for the release and flotation of valuable minerals. The aqueous sludge or slurry of the particles is introduced into a stirred mixing vessel 46 for the addition and mixing of suitable stowage reagents. If silica or wreckage is to be floated (reverse flotation), a cationic size 25 or or an anionic collector (for calcium-activated silica) is added and mixed with the aqueous slurry in a wetting vessel 46. If iron oxide is to be floated, an anionic collector such as fatty acids is suitable. added to the aqueous slurry and mixed with 30 tn in a wetting vessel 46.

Several suitable treatment reagents can be used, depending primarily on the material to be treated and the type of foaming. The treatment reagent disclosed in U.S. Patent 4,132,633, which is incorporated herein by reference, is highly effective for iron ore when charged with an anionic collector. This treatment reagent is formed by mixing a multivalent metal salt with an alkali metal silicate. The treatment reagent is usually added to the slurry and thoroughly mixed with it before adding the collector. After the collector is added to the wetting vessel 46, the slurry is mixed for a sufficient time to ensure even distribution of the collector throughout the slurry.

5 In some cases, it may be necessary to add a small amount of fuel oil and / or conventional blowing agent to the slurry. When used, the blowing agent can be mixed into the slurry before, after or together with the collector. If the blowing agent is added separately, the slurry 10 is mixed for a sufficient time to ensure even distribution of the blowing agent in the slurry.

after mixing, the slurry is removed from the wetting vessel 46 by a pump 48 and introduced into the column through the slurry inlet 18.

The sludge, air and wash water flow rates can be adjusted to achieve material balance, resulting in the most efficient separation of floating particles (i.e. iron oxide) from non-floating particles (i.e. waste rock).

The described apparatus and method have several advantages over conventional flotation apparatus and methods. They provide all the advantages of conventional flotation columns and further provide increased air-particle contact, i.e., minimize the need for a special device at the bottom of the column to generate fine bubbles, and require less water and energy. And more importantly, floating particles such as iron oxide can be more effectively · separated from non-floating particles such as waste rock by single-stage flotation. Thus, a conventional flotation column usually requires at least two flotation steps to obtain the same amount of iron oxide from low quality iron ore.

In addition to single-stage operation, the device can be used with conventional flotation machines and two or more can be used in series.

The following examples have been selected to illustrate the invention, and the invention is in no way limited thereto.

Example 1

A series of laboratory experiments were performed on a test column, il 9,75280 from a 50.8 mm (2 inch) inner diameter tube 2.44 m (8 ft) long and almost completely filled with 50.8 mm (2 inch) long conventional brass tower packing cylinders.

5 Test Batches -10 mesh oxidized Taconite ore (obtained from the Cascade deposit owned by the Cleveland-Cliff Iron Company) was ground in batches containing 60 wt / $ solids in a can mill for about 20 minutes to produce a slurry or slurry. , of which about 10 80 weight-fi passes through 500 mesh. The slurry was treated with a wetting reagent prepared according to U.S. Patent 4,132,635 and the pH was adjusted to 8.8 by the addition of soda or sulfuric acid. The resulting batches of slurry were separately placed in a stirred tank where the fatty acid collector (PÄI-IAK-4) 15 No. 2 fuel oil and blowing agent were added and mixed into the slurry.

A treated batch of slurry containing 20% solids was continuously pumped from a stirred tank into the center of the column.

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at about 130 cnr / min. Water was introduced into the Si-20 weather near the top of the column at a flow rate of about 50 cm 2 / min and air was introduced near the bottom of the column at a flow rate of about 8 l / min.

Batches of concentrate and waste, taken from the top and bottom of the column, respectively, are collected and analyzed for iron-25 content. The results of the descriptive experiments are summarized in Table I.

The mild results illustrate the excellent separation efficiency in a flotation column arranged and operating in accordance with the invention, even though only one degree of flotation has been used.

30 Example 2

A series of pilot plant experiments were generally performed on a column arranged as shown in Figure 1 and on a conventional 8-stage WEKC0 Fagergre flotation machine. The column was 6 m (20 ft) long and had a cross-section of 35 of 18.4 cm x 18.4 cm (7 1/4 inch x 7 1/4 inch) and contained six 91 cm (3 ft) long fill compartments. Each filling compartment had 5 layers of corrugated sheets. The corrugation of the sheets was 3.2 mm (1/8 inch) high and traveled at an angle of 10,75280 at 45 ° to the horizontal, and the adjacent layers or compartments were oriented at an angle of 90 ° to each other.

The oxidized Taconite ore was ground to about 75% -500 mesh and formed into a slurry. The treatment reagent prepared according to U.S. Patent 4,132,635, an anionic collector (PAKAK-4), and No. 2 fuel oil were mixed with the slurry. One stream of treated slurry containing about 20 wt. $ 6 solids was pumped into the feed section of the column at a feed rate of about 68 kg / h (150 pounds / h) and the other stream of the same slurry was treated in a conventional flotation machine. Air at a pressure of about 10-12 psig was introduced into the column through the gas inlet at a rate of about 8.55-14.25 m 2 / h (300-500 ft / h) and the wash water was injected into the flotation machine at a rate of about 114-190 l / h (30-50 gallons / h).

Concentrations and wastes from the column and conventional flotation machine were collected and analyzed for iron concentrations. The results of these experiments are summarized in Table II. Under the heading "used machine" in Table II, "A" means the device according to the invention and "B" means a conventional foaming machine.

From these results, it can be seen that the single-stage flotation with the column and method according to the invention gives a higher quality concentrate and / or a higher recovery than the eight stages of a conventional flotation machine.

From the foregoing description, one skilled in the art can readily ascertain the essential features of the invention, and while remaining within the scope of the invention, various modifications may be made to apply it to various uses and conditions.

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Claims (10)

13 75280 A method for enriching floating material by flotation in an aqueous slurry comprising a mixture of floating and non-floating particles, the method comprising using a tubular flotation column having a top and a bottom, preparing an aqueous slurry for flotation separation of the particles therein and introducing the resulting slurry into a column at the point between the bottom, the wash water is introduced to the top of the column for downward flow, a pressurized inert gas is introduced to the bottom of the column for upward flow, the floating portion containing the liquid slurry is removed from the top of the column, that top and bottom filling means are further used which define a large number of flow channels which circulate between said intermediate point and the upper part of the column and between the intermediate point and the lower part, respectively, wherein the slurry is fed to the point between the top and bottom filling means so as to flow through the flow channels of the bottom filling means, and the pressurized inert gas is fed from below the bottom filling means so as to flow up through the flow channels of the bottom filling means, whereupon the gas decomposes which are in close contact with the particles of liquid slurry in the flow channels of the underfill means, and the wash water is fed above the overfill means so as to flow downwards through the flow channels of the overfill means and the waste portion is removed below the underfill means. A method according to claim 1, characterized in that the slurry consists of a mineral containing a mixture of valuable mineral particles and waste particles, and the slurry is prepared for flotation by treating with flotation reagents effective to promote separation of valuable minerals and waste by flotation. m 75280 Method according to Claim 2, characterized in that the mineral ore is a low-grade iron ore. Apparatus for carrying out a method according to any one of the preceding claims, comprising a tubular flotation column comprising a top and a bottom, sludge feed means for introducing aqueous sludge into the column between the top and bottom, means for introducing wash water into the top of the column for inward flow for upstream flow to the bottom of the column, means for removing the floating portion of the aqueous slurry containing floating particles from the top of the column, and means for removing the waste portion containing the non-floating particles of the aqueous slurry from the bottom of the column, characterized in that the filling means (24) ) and the lower part (16) and define a large number of small flow channels which meander between the upper part (14) and the lower part (16) and that the gas flows upwards through the flow channels and is distributed into fine bubbles that are in close contact with: particles of liquid sludge in the flow channels. Device according to claim 4, characterized in that the filling means (24) comprise a plurality of vertically arranged plates (40) and spacer means (42) for laterally spacing the plates (40) to define a plurality of flow channels between adjacent plates. Device according to Claim 5, characterized in that it comprises a plurality of vertically adjacent, separate sections (38a-f) of the plates (40). Device according to claim 6, characterized in that the compartments (38a-f) are oriented such that in each of said compartments (38a-f) the vertical planes of the plates (40) are at right angles to the vertical planes of the plates (40) of adjacent compartments. Device according to one of Claims 5 to 7, characterized in that the spacer means comprise corrugated rows (42) in each plate (40) which run obliquely across the plate plane. Device according to Claim 8, characterized in that the corrugations of the adjacent plates (40) run in transverse directions. Device according to one of Claims 4 to 9, characterized in that the column (12) comprises an unfilled chamber (44) in the vicinity of the sludge inlet (18) for receiving the sludge. 16 Patent Scrap: 7 5 2 8 0