Froth flotation machine

Abstract: The invention relates to an improved flotation cell design for the mining industry. The flotation cell includes a cylindrical froth flotation unit 52 and a unique hexagonal overflow froth launder 84. The design optimizes the froth flotation process and allows for the economical utilization of the honeycomb packing arrangement of cells.

Description: This invention relates to an improved flotation machine and cell design for the mining industry and, in particular, for the process of separating minerals from ore through flotation of the mineral and removal from the ore. In the mining industry, flotation is the primary method for concentrating and recovering minerals utilizing copper flotation, fine coal flotation, iron ore flotation, phosphate rock and potash flotation, base metal sulfide flotation and precious metal sulfide flotation. Flotation is essentially a three phase unit process involving the intimate mixing of finely ground solids, liquids, and air to concentrate desired minerals from gangue by floating one away from the other. In carrying out the flotation process, the ore is crushed into finely ground solids and mixed with liquids to form a slurry or pulp. The slurry is then aerated using a flotation machine to achieve solid/liquid mixing and air dispersion through an internal air source or by a self-aspirating flotation machine. U.S. Patent Nos. 4,425,232 and 4,800,017 describe a flotation separation apparatus and method comprising a flotation machine provided with a rotor-stator pump assembly submerged in a slurry and in which rotor blades agitate the slurry thoroughly mixing the solids and liquid and introducing air to the mixture for aeration and generation of froth or foam on the surface of the flotation cell. Particles of minerals attach to carrier air bubbles which are naturally buoyant and form the froth, this being the effective mechanism for mineral recovery. The froth is removed hydrodynamically from the top of the slurry mass together with the entrapped mineral particles which are recovered as froth is accumulated and dewatered. Conventional cell tank designs, as depicted in FIG. 1 for instance, and labelled prior art, are rectangular (cf. US-A-4 800 017) or U-shaped (cf. US-A-4 425 232) and use a long froth overflow launder and partition plates. The froth overflow launder is generally longitudinally placed along side the tank, though some designs make use of a cross launder along the partition plate. Froth containing the desired minerals, which has risen with the air bubbles created by the rotor or mixer, overflows onto the launder and runs into a discharge pipe for collection. Cells having a polygonal cross-section are similarly known in the art (cf. DE-C-0 807 262 or US-A-3 409 130). The hexagonal cell as disclosed by DE-C-0 807 262, having an internal channel for froth collection, enables the honeycomb arrangement of several cells. Prior tank and overflow launder designs have proved inefficient and costly. The reinforced rectangular tank design contains corners and flat sides which must be heavily reinforced against bulging forces. Further, corners which exist in the rectangular and polygonal design promote waste due to eddy currents and/or stagnant pockets. Launders are built independent from the flotation tanks and are often self-supporting. It is an object of this invention to produce an economical cell and froth overflow launder design which provides a high ratio of froth overflow lip length to cell tank volume, with less troublesome cross launders. Cross launders provided in the prior art interfere with flow patterns and encroach on useful flotation volume. It is a further object of this invention to produce a flotation cell and froth overflow launder design wherein the flotation tank volume is fully utilized due to the elimination of all corners. Further, it is an object of this invention to produce a flotation cell and overflow froth launder design that can be arranged to maximize building floor space and thereby minimize costs. This invention is directed to these objectives and others with specific reference to flotation equipment. SUMMARY OF THE INVENTION The improved flotation machine, cell and overflow froth launder design according to the invention includes a cylindrical tank and a unique hexagonal overflow launder configuration as delineated in claim 1. Preferred embodiments of the invention are defined in dependent claims 2-6. The unique hexagonal overflow froth launder allows for a unique nesting of adjacent rows of cells into a beehive or honeycomb arrangement. Each of the cylindrical tanks contain a rotating mechanism which operates to create the bubbles to which desired minerals adhere for froth production. The hexagonal overflow froth launders contain a plurality of bottom discharge outlets for collection of the froth. The hexagonal launders are integral with the cylindrical tanks, with the tank wall forming one side of the launder. The unique cylindrical cell design and hexagonal peripheral overflow froth launder provides a high ratio of froth overflow lip length to cell tank volume often eliminating the need for troublesome cross launders. The cylindrical shape and circular cross-section of the cell eliminates troublesome corners which produce waste due to areas of stagnation or eddy current formation. The cylindrical shape is self-reinforcing and avoids flat sides that would require heavy reinforcing to protect against bulging. Further, the unique hexagonal overflow launder design facilitates a beehive or honeycomb nesting arrangement of the flotation tank thereby effectively utilizing building space and minimizing building expenses. The above and other objects, as well as the advantageous features of the invention will become more clear from the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of a prior art configuration; Figure 2 is a top plan view of a plurality of tanks in accordance with the invention nested in beehive or honeycomb arrangement; Figure 3 is an elevational view of the arrangement of Figure 2; and Figure 4 is a perspective view of a single cylindrical cell and hexagonal overflow froth launder in accordance with the invention. DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, particularly to Figure 1, the prior art flotation cell and overflow froth launder design includes a feed box 10 wherein finely ground ore is mixed with a liquid and fed into the flotation apparatus 12. The apparatus 12 contains two compartments or cells 14 and 16, respectively. In each of the cells there is provided a rotation device or mechanism, 18 and 20, respectively, which produces air bubbles for froth flotation. Further, there is provided a discharge box 22 for removal of unseparated solid and liquid. Provided along the longitudinal edges, 24 and 26, of the cells are conventional froth overflow launders, 28 and 30, respectively. Lastly, the conventional flotation apparatus 12 contains a partition plate and a cross froth launder 32 thereon, which divides the apparatus into two cells. Contained in the bottom of the froth overflow launders, 28 and 30, are froth discharge outlets 34 and 36. The prior art structure, as depicted in Figure 1, is lacking in its inefficient shape and launder arrangement. Referring to Figures 2 and 3, the improved flotation machine and overflow froth launder arrangement is depicted. The flotation machine 50 includes a plurality of cylindrical flotation cells 52, 53, 54, 55, 56, 57, 58 and 59. Focusing on three of the cells for analysis, they each contain a rotation mechanism, 60, 61 and 62 for production of bubbles to be utilized in mineral separation. Feed boxes 64 and 66 are provided as inlet ports for feeding liquid and finely ground ore into the machine. Discharge boxes 68 and 70 are provided for the removal of unseparated solids and liquids. Cell tank edges 72, 74, 76, 78, 80 and 82 are bordered by hexagonal overflow froth launders having sides 84, 86, 88, 90, 92 and 94, which contain froth discharge outlets 96, 98, 100, 102, 104 and 106, respectively. Mineral rich froth overflows from cells 52, 54 and 56 into the bordering hexagonal overflow froth launders in an efficient and optimized fashion. Due to the hexagonal configuration of the cells and their launders, the flotation devices nest together in a unique and efficient beehive or honeycomb fashion. Shallow, cross launders are employed to enhance the arrangement. Further, there is provided, if desired,junction boxes 108 and 110 to accommodate descending levels of an installation. Such an installation will compensate for loss of head as the slurry passes through the cell array. Figure 3 illustrates the utilization of the junction box 108 to connect descending groupings of cells 56 and 57. Figure 4 is a perspective view of a flotation cell embodying the invention. Cylindrical cell 120 contains a hexagonal overflow froth launder 122. Launder discharge outlet 124 can be attached to an outlet pipe for collection of mineral rich froth. The present invention provides an advantageous structure and operation. Cylindrical cell construction eliminates heavy reinforcement requirements as well as undesirable turbulent corner effects which harm desired efficient froth removal of minerals. Further, hexagonally shaped overflow froth launders optimize froth collection and allow for a unique beehive nesting arrangement. The foregoing advantages are particularly advantageous with large flotation projects thereby minimizing costs and enhancing mineral collection. While there has been described a particular embodiment of the invention, it will be apparent to those skilled in the art that variations may be made thereto without departure from the scope of the appended claims.

Claims: A froth flotation machine comprising at least one upright flotation cell (52-59; 120), means (64, 66; 108, 110) for admitting liquid and ore to the cell, means (68, 70; 108, 110) for removing solids and liquids from the cell, means (60-62) for aerating the mixture in the cell to produce a mineral-rich froth, and a froth launder (84; 122) adjacent the upper end of the cell, characterised in that the cell is cylindrical, and the froth overflow launder is hexagonal and extends circumferentially around the upper end of the cell. A froth flotation machine as claimed in claim 1 comprising: an inlet box (64, 66) attached to said cell; and a discharge box (68, 70) attached to said cell. A flotation machine as claimed in claim 1 comprising a plurality of flotation cells and hexagonal overflow froth launders arranged in a honeycomb configuration. A flotation machine in accordance with claim 1 comprising an array of at least two rows of cylindrical flotation cells with each of said cells provided with a hexagonal overflow froth launder, further characterized in that the hexagonal launders in one of said rows contact hexagonal launders of an adjacent row in a honeycomb configuration. A flotation machine in accordance with claim 1 comprising an array of at least two rows of upright cylindrical flotation cells (52-59) provided with hexagonal froth overflow launders, wherein said means for admitting liquid and ore to a cell is an inlet port (64,66) in the cell at one end of each row of cells for feeding into said end cell finely divided mineral ore and a fluid, said means for removing solids and liquids from a cell is a discharge port (68, 70) in a cell at the opposite end of the row of cells for removal of unseparated fluid and ore from said cell, and said means for creating the mixture in the cell is a rotation mechanism, further characterized in that said hexagonal overflow froth launders of a first row of cells contacts the hexagonal overflow launders of an adjacent row of cells in a honeycomb configuration. A flotation machine in accordance with claim 4 or 5 further characterized in that a junction box (108, 110) is provided in each of said rows to separate cells.

Inventors: LAWRENCE GEORGE A, LAWRENCE, GEORGE A.
Applicants: DORR OLIVER INC, DORR-OLIVER INCORPORATED
Application year: 1993
Main classification: B03D1
IPC codes: B03B11, B03D1