- 1 -

PNEUMATIC FLOTATION TECHNOLOGY - EXPERIENCE IN THE CHILEAN MINING INDUSTRY

Eng. M.Sc.Eng Samuel Sánchez-Pino, Ingeniería de Minerales S.A. General Manager 1423 Ave. Padre Alberto Hurtado Antofagasta, Chile samuel@ingenieriademinerales.cl. Dr. Eng. Rainer M. Imhof, Julian Brown C. Eng, Maelgwyn Mineral Services Limited Leharweg 23, Dorsten 46282, Germany and 4a Mostyn Street, Llandudno, Wales, U.K., LL30 2PS mms@maelgwyn.com Eng. Samuel Sánchez-Baquedano, Flavio Rojos-Tapia, Ingeniería de Minerales S.A. Process Metallurgist 1423 Ave. Padre Alberto Hurtado Antofagasta, Chile Key Words: Flotation, Pneumatic Flotation, Copper Flotation, Quartz-Silicate Flotation.

ABSTRACT

Pneumatic flotation was introduced to the Chilean copper mining industry in 1993 by Ingeniería de Minerales S.A., being first implemented in 1994/95. The technology is based on the designs of Dr. Rainer Imhof and from Chilean copper processing experience.

Pneumatic flotation has been successfully applied for sulphide and oxide copper minerals, copper slag, iron ores (reverse flotation) and gold, and also appears promising for molybdenum concentrates. Difficult separating conditions have been encountered in various process stages, including roughing, cleaning and scavenging. Pneumatic flotation can essentially be applied in any separation where differences exist between mineral and gangue interactions with water. Even high relative density slurries can be processed because the range of amenable particle sizes is quite broad, and the number of cleaning stages required has not exceeded one in our experience.

The performance efficiency of this technique can be explained by the high gas hold-up and the effective micro-turbulences which boost attachment to the bubbles, resulting in much reduced flotation time. Economic benefits include lower energy consumption, lower maintenance costs, simplicity and reliability and minimal plant area requirements.

In view of the Chilean mining industry experience, it can be concluded that pneumatic flotation can be regarded as a highly effective alternative to conventional methods in mineral processing.

- 2 -

INTRODUCTION

The technology originates from pneumatic flotation developments in the 1970s in

Germany by Prof. Simonis (Technical University of Berlin) and Prof. Bahr (Technical University of Clausthal). Since then Dr. Rainer Imhof has been known widely for his contributions to design at Ekof, KHD, Allmineral and most recently Maelgwyn Mineral Services where he is Technical Director (Imhof, 1998). Ingeniería de Minerales S.A. has been involved with the technology development by Dr. Imhof for more than ten years and is broadly experienced with flotation, from Wits University and Mintek in South Africa (Sánchez, 1990).

There are many academic treatise available concerning the separating phenomena and methods for better control in traditional flotation. Pneumatic flotation, however, is a viable means to separate feed conditions, particle and bubble interactions, and phase separations (froth and tailings). In combination this provides a completely different flotation concept with the flexibility and simplicity for a realistic alternative in the Chilean mining market.

The first plant using this kind of flotation technology was in 1993/94 as a means to provide a fast separation of sulphide and to re-use existing mechanical cell circuits to float oxide copper. In this way only two rougher cells were required, and together with one cleaner stage, were sufficient to float sulphide to sale quality (Sánchez, 1997). Flotation of slag containing around 1% copper was another important application, with two rougher cells working in series and a single stage cleaner incorporating two cells in series, for 3300 tons/day (Barrera, 1996). Both of these industrial applications used sea water.

Modifying an old-style flotation plant consisting of two circuits to float chalcopyrite and gold provided us with an interesting experience to see how effective the change could be when new technologies are used. The two circuits processed 18,000 tons per month (600-700 t/d), using 30 cells in total including rougher-scavengers, eight cleaners two re cleaners. With the addition of two rougher cells and one cleaner stage with two cells in series this increased capacity to 2,300 t/d, (Tapia, 1995).

One of the largets pneumatic flotation plants in the world is now working in Chile, to remove silica and silicate from magnetite concentrates. The plant has a capacity of 13,390 t/d of intermediate concentrate, a slurry density of 1.47 (40 % solids), and a specific gravity of solid of 5.05 working with sweet water. The plant is a stand-alone flotation circuit and is fully automated (Melendez, 2002). PNEUMATIC FLOTATION DESIGN

Flotation technology could be categorised into mechanical agitation cells, column cells and pneumatic cells, the latter which were developed mainly in Germany in the 1970s. Professors Wolfgang Simonis and Albert Bahr developed Jet Flotation (Simonis, 1981) and the Bahr cell (Bahr, 1982) mainly for coal. Imhof’s designs, however, have been implemented for a wide range of industrial applications in the world including metallic and industrial minerals. Most industrial minerals applications are in Europe, and most metallic mineral applications are in Chile.

Fig. 1 – 2 illustrate the main designs from Imhof, and which are used in the mineral industries worldwide. The principle feature of the technology is a separate device for the aeration unit from which the outlet mixture flows into the separating vessel, where the slurry particles are predominantly in close bubble contact. The separator uses a high gas hold-up and effective micro-turbulences in the medium which boost particle-bubble contact, while ensuring no dead zones and very short residence times.

The self aspirating aeration unit at the top of the cell is an important component of this technology. The slurry is pumped with enough fluid energy to induce a large quantity of air in the form of fine bubbles with extensive micro-turbulences. Due to the high velocity in the device

- 3 -

silicon carbide (SiSiC) components are required to avoid wear. Normally the slurry pressure for feed to the aeration unit is 2 – 2.5bar.

Consequently, the conditioning time of the slurry is more important, due to the short resident time with high gas hold up. The particles have to be prepared for collision and attachment before entering the vessel. The froth separation process involves lower turbulence to avoid entrainment of gangue particles in the concentrate.

A further useful feature of the technology is the froth and interface level control, for example the froth height can be varied easily with a precision of 2-3 cm through a range to 140 cm, which is a parameter for the enrichment factor. The cross sectional surface area for froth removal is also variable according to the mass to be removed with the froth and the kind of froth in question – in other words: for scavenging low froth thickness and small areas are required for the froth to flow, and for cleaning high froth thickness and large areas are required. Recycling a portion of the cell tailings discharge, such as in a mill circuit, provides the means to increase recovery in the same cell. In this way it is possible to reduce the number of cells in series, i.e. 2 instead of 3 for the same recovery. Furthermore the high gas hold up in the down-comer promotes recovery. The fast kinetics of pneumatic flotation make it possible to operate with shorter and fewer circuits to produce optimal products. In our experience two cells for roughing are sufficient. In most applications the primary concentrate is of sufficient grade that only a single cleaner step with 2 cells in series is required. Fig. 2 shows a completely different cell. Because low residence time is already achieved for the aeration and collection process the greatest time dependence is the residence time to separate bubbles from slurry in the vessel. Sedimentation and buoyancy are the main parameter to separate bubbles, so the forces are multiplied in the centrifugal field and accelerate the separation dramatically. The retention time of the slurry in this system is only about 25 – 30 s, which results in small apparatus with high capacities.

Fig. 1 Second Design In Chile (1996-2002)

- 4 -

Fig. 2 Third Design In Chile (2003)

INDUSTRIAL APPLICATIONS IN CHILE MINERA MICHILLA S.A.

The company Minera Michilla is located about 1400 km north of Santiago in the coastal zone of the Atacama desert. The process plant was normally supplied with a wide range of grades and different type of minerals from a variety of underground and open pit mines in the company. Compositions ranged 2.6 – 3.4 % Cu total, 1.9 – 2.6% Cu sulphide and 0.9 – 0.6% Cu oxide, and sea water was used. Common mineralogy included chalcocite, bornite, covellite, chalcopyrite, atacamite, and chrysocolla, (Fuentes, 1995) In order to increase oxide recovery and simultaneously to improve the performance of sulphide material in the process with a low investment, Michilla chose to introduce pneumatic flotation: two cells operated as roughers and a single third one cleaned the rougher concentrate in one step. The old mechanical circuit continued to process oxides after treatment with sodium sulphide. For higher feed grades there still remained the option to use the old mechanical cleaners, which were earlier needed for cleaning, before pneumatic flotation was implemented. After a while, pneumatic flotation was introduced in the oxide flotation circuit. The conventional circuit changed with the time and its evolution can be observed as follows:

- 5 -

Fig. 3 Original mechanical cells circuit (only sulphide flotation)

Fig. 4 Initial pneumatic cells circuit ( oxide and sulphide concentrate production and higher throughput)

Fig. 5 Second pneumatic flotation circuit (sulphide and oxide)

- 6 -

Table 1 Rougher Tests (single pneumatic cell)

TEST FEED TAILING SULPHIDE CONC

Cu wt% Cu wt% Cu wt% Total Sol Insol Total Sol Insol Total Sol Insol 1 2.82 1.61 1.21 1.51 1.21 0.3 19.88 3.73 16.15 2 3.33 1.11 2.22 1.61 0.96 0.65 17.25 2.27 14.98 3 3.33 1.26 2.07 1.41 0.86 0.55 32.68 3.03 29.66 4 3.73 1.21 2.52 1.82 1.05 0.76 22.6 2.42 20.18

TEST COPPER

RECOVERY GENERAL

CONDITIONS Total Sol Insol 1 50,27 36,77 76,63 SOLIDS % w/w 27 - 42 2 56,97 23,42 73,93 % -200# Ty 46 - 33 3 60,26 44,33 74,82 % +65# Ty 12 - 18 4 56,69 22,06 72,57 pH 9.5 - 10.5

Table 2 Comparison between both plant configurations illustrated: mechanical cells only (Fig. 4) and mixed circuit (Fig. 5) TEST FEED TAILING SULPHIDE CONC OXIDE CONC

Cu wt% Cu wt% Cu wt% Cu wt% Total Sol Insol Total Sol Insol Total Sol Insol Total Sol Insol

1 4.48 1.49 2.99 1.34 1.02 0.32 42.05 7.01 35.04 2 4.47 1.08 3.39 1.25 0.84 0.41 43.09 4.06 39.03 3 3.53 1.18 2.35 0.78 0.75 0.03 42.48 3.58 38.90 6.52 3.74 2.78 4 3.33 1.00 2.33 0.70 0.67 0.03 50.35 4.65 45.70 5.38 2.28 3.10 5 4.24 0.95 3.29 0.59 0.56 0.03 49.14 3.44 45.70 6.44 4.05 2.39 6 4.43 1.05 3.38 0.87 0.72 0.15 46.41 2.73 43.68 7.23 4.20 3.03

TEST COPPER RECOVERY GENERAL

CONDITIONS Total Sol Insol 1 72.28 36.33 90.14 SOLIDS % w/w 36 - 38 2 74.20 28.81 88.73 % -200# Ty 48 - 45 3 81.13 43.54 98.02 % +65# Ty 20 - 25 4 81.27 39.95 98.95 pH 8.3 5 87.77 48.22 99.21 6 82.87 40.32 96.11

- 7 -

Fig 6. Pneumatic cells at Michilla

Fig. 7 Overall comparison of technology effects (Sánchez, 1997)

- 8 -

Fig. 8 Third pneumatic flotation circuit sulphide and oxide

Table 3 Results from Third Pneumatic Circuit The table indicates results from the alternative circuit which was tested at production scale, in order to improve the oxide concentrate grade.

TEST FEED TAILING SULPHIDE CONC OXIDE CONC Cu wt% Cu wt% Cu wt% Cu wt% Total Sol Insol Total Sol Insol Total Sol Insol Total Sol Insol

1 2.86 0.83 2.03 0.57 0.48 0.09 45.40 2.51 42.89 23.00 15.88 7.12 2 2.46 0.74 1.72 0.57 0.42 0.15 39.19 1.88 37.31 28.34 20.13 8.21 3 2.40 0.47 1.93 0.55 0.37 0.18 47.80 1.49 46.31 13.80 2.92 10.88

TEST COPPER RECOVERY GENERAL

CONDITIONS Total Sol Insol 1 81.26 45.62 95.8 SOLIDS % w/w 36 - 43 2 78.11 46.41 91.8 % -200# Ty 48 - 55 3 77.78 23.23 90.96 % +65# Ty 20 - 25

- 9 -

The application of this technology at Minera Michilla S.A. improved flexibility in the circuits at high capacity allowing the plant to adapt to changes of grades and mineral compositions. For both kinds of product, sulphide and oxide concentrate, the production was increased from 2.4 t/h to a range of 4.0 – 5.2 t/h. Throughput of the plant increased from 40 t/h to 80 t/h and sometimes even up to 100 t/h. 2.- COMPAÑÍA MINERA TAMAYA S.A. Minera Tamaya is located about 450 km north of Santiago de Chile. An expansion project was initiated to increase capacity from 18,000 t/m to 23,000 t/m treatment rate for a chalcopyrite – gold mineral ore (Tapia, 1995). Pilot tests were conducted under production conditions in order to evaluate pneumatic flotation technology. Two parallel circuits with mechanical cells normally operated in production, due to the plant feed originating from different mines, with different grades and mineralogy. Fig. 9 shows the original conventional circuits with mechanical cells.

Fig.9 Mechanical cells circuit The overall tests results are shown in Table 4 where one of the conventional industrial circuits is compared with one pneumatic cell.

- 10 -

Table 4

Single pneumatic cell performance Comparison of single pneumatic cell with mechanical circuit type 2

MINERALOGY Au RECOVERY % Cu RECOVERY %

Pneumatic Mechanical Pneumatic Mechanical

A 77.2 78.79 84.63 82.62 B 59.38 56.24 53.43 50.94 C 63.06 78.93 36.37 56.64 D 86.62 83.38 92.66 83.99

Additional pilot tests were conducted treating the tailings from the same industrial circuit (see Table 5).

Table 5 Tailings treatment with pilot pneumatic cell from type 2 circuit

GRADES RECOVERY % CONC RATIO Au (g/t) Cu (tot %) Au Cu (tot) Au Cu Feed 0.6 0.14 54.29 22.57 11.67 69.00 Concentrate 3.8 2.18 Tailings 0.3 0.11 Feed 0.5 0.05 43.00 22.86 20.00 28.00 Concentrate 4.3 0.32 Tailings 0.3 0.04 Feed 0.5 0.06 42.03 17.58 29.50 91.00 Concentrate 6.2 0.96 Tailings 0.3 0.05

As a consequence of the pilot scale tests, Minera Tamaya decided to change the mechanical flotation circuits to pneumatic flotation, also drawing on the experience at Minera Michilla, which belongs to the same company. Both mechanical circuits (see Fig. 9) were changed to pneumatic flotation (see Fig. 10) which comprised two pneumatic cells of 2.5 m diameter in series as roughers, and two cells of 2.0 m diameter in series as cleaners.

- 11 -

Fig. 10 New pneumatic flotation plant at Tamaya (800 t/d)

Table 6 Feed circuit No. 2 rougher flotation comparison

GRADES RECOVERY % CONC RATIO Au (g/t) Cu (tot %) Au Cu (tot) Au Cu Pneumatic Cell Feed 3.4 1.11 72.63 82.72 24.70 24.51 Concentrate 61 22.5 Tailings 0.97 0.2 Feed 7 1.05 72.24 81.85 35.00 21.14 Concentrate 177 18.17 Tailings 2 0.2 Feed 9.1 0.52 71.63 77.51 38.63 39.20 Concentrate 251.8 15.8 Tailings 2.65 0.12 Average 72.17 80.69 32.78 28.28 Mechanical circuit Feed 5 1.22 92.19 93.61 5.92 7.46 Concentrate 27.3 8.52 Tailings 0.47 0.09 Feed 9.45 1.03 89.66 93.24 7.84 7.69 Concentrate 66.4 7.39 Tailings 1.12 0.08

- 12 -

(Table 6 cont.) Feed 9.5 0.62 88.83 87.77 6.33 6.34 Concentrate 53.4 3.45 Tailings 1.26 0.09 Average 90.23 91.54 6.70 7.16

The new Tamaya flotation concentrator, comprising only pneumatic cells, improved production economics dramatically. Additionally the plant was highly flexible, with low maintenance requirements, and contained in a compact area with a high degree of automation. 3. COMPAÑÍA MINERA MAITENES The Los Maitenes concentrator treats copper slag arising from Empresa Nacional de Minería Smelting, which belongs to the government. The plant is located 150 km north-west of Santiago de Chile. Basically the project requirements were to process 3000 t/d, containing 1.30% total copper, with a grind of 90% -200 mesh (Tyler) for the feed, at 30% solids (w/w) pulp density using sea water. Pneumatic flotation laboratory scale tests provided results (Table 7) which demonstrated the potential of an alternative to conventional flotation. Samples from the slag dump were used for the testing. In conclusion the circuit of Fig. 11 was proposed to Los Maitenes, to be a fully automated plant (Barrera, 1996). The initial results from the plant were somewhat different to expectations, in terms of recovery, while product grade was acceptable in the range of 25 – 27 % Cu total. The lower than anticipated feed grade was considered to be partially responsible, as it was only in the range of 1.10 – 0.91% Cu total, and also the grind size of only 80 % -200 mesh. This meant that liberation was insufficient, and hence recovery was lower than expected. The problem was concluded to be caused by the mineral grain size in the slag. Rapid quenching of the slag after the smelting process produces ultra fine metallic Cu particles and effectively only a grind to more than 90 % -200 mesh would have improved the recovery.

Table 7 Preliminary results from conceptual analysis

Flotation Process ROUGHER CLEANER SCAVENGER RECLEANER TAILINGS FEED

Rec.

% Cu % Rec.

% Cu % Rec.

% Cu % Rec.

% Cu % Cu % Cu % 1 83 7.99 91.00 10.44 85.60 0.84 56.90 23.10 0.24 1.24 2 77.2 5.66 89.2 9.35 87 0.78 55.4 21.25 0.32 1.24

- 13 -

Fig. 11 Proposed circuit to float copper slag

Fig. 12 Industrial slag flotation Plant ( 3,000 t/d) CODELCO CHILE DIVISIÓN CHUQUICAMATA

An industrial pneumatic flotation cell of 4.5m diameter is already operating at the Molybdenum Plant at Chuquicamata. Intensive testing was carried out at a normal feed rate to the Moly Plant, i.e. 250 m3/h to 400 m3/h slurry with usual feed variations. Flotation products were recycled to the large capacity storage tank. The range of conditions shown in Table 8 present an

- 14 -

overview of normal operations. Additionally the height of froth was tested between 40 - 140 cm and, using a wash water device it was possible to increase the concentrate grade to contents of 36% Mo – even though the wash water distribution was not optimised.

The main target for integration of the cell in the production circuit was to test the cell as a pre-rougher to see whether the high consumption of NaSH can be reduced. NaSH is used to depress the chalcopyrite in the mechanical flotation cells. The results were positive, due to the rapid kinetics of the pneumatic flotation process.

The performance analyses of the campaigns were carried out by engineers from Chuquicamata. The commercial interest is to extend the existing mechanical flotation by using the pneumatic cell and to reduce reagent costs while improving the overall performance of the flotation circuit. This means increasing the average recovery by around 5%. The experimental tests will be continued by operating the cell for a longer period in order to analyse the availability.

Table 8 Experimental Parameters on a real

operational base (single cell) FRESH FLOW (m3/h) VARIABLES 250 300 400 43,0 37,6 35,0 %SOLIDS (fresh feed) 45,8 46,6 41,5 46,0 51,6 45,5 40,0 36,4 25,8 %SOLIDS (compound feed) 35,8 30,9 37,0 35,5 37,2 35,2 1,524 1,43 1,389 DENSITY (fresh feed) 1,579 1,594 1,497 1,582 1,703 1,572 1,471 1,41 1,277 DENSITY (compound feed) 1,414 1,336 1,416 1,383 1,428 1,396 9,67 9,77 11,45 pH (fresh feed) 9,56 9,31 10,30 9,73 10,02 11,22 11,04 10,98 11,6 pH (compound feed) 11,33 11,07 11,05 11,09 11,44 11,47 5,225 0,498 0,304 Mo grade % (fresh feed) 1,185 0,860 0,552 1,479 1,240 0,478 19,227 12,880 3,768 Mo grade % (concentrate) 10,680 7,720 4,000 10,559 16,950 11,920

- 15 -

(Table 8 cont.)

3,078 0,320 0,238 Mo grade % (tailing) 0,354 0,342 0,346 0,553 0,656 0,436 48,920 36,650 23,170 Recovery Mo % 72,530 48,990 21,810 66,070 63,060 40,850

Fig. 13 Effect of pneumatic flotation working as pre rougher cell in a Mo circuit

(Gonzalez, 2002)

Fig. 14 Industrial cell testing at Mo Plant

PRE ROUGHER PNEUMATIC CELL EFFECT

60

65

70

75

80

85

90

95

100

1 2 3 4 5 6 7

RANGE OF ALTERNATIVE

Mo

REC

OVE

RY

STANDARD FLOTATION CIRCUIT WITHOUT PNEUMATIC CELL STANDARD CIRCUIT WITH

PNEUMATIC FLOTATION AS PRE ROUGHER

- 16 -

Fig. 15 Froth from pre rougher pneumatic cell

HUASCO MINING COMPANY

Huasco Mining Co. (CMH) is located about 800 km north of Santiago de Chile. Los Colorados mine and the Pellet Plant are the main industrial center in this area. They are owned and managed by Compañía Minera del Pacífico (CAP) and Mitsubishi from Japan.

In the process development department at CMH pellet plant there has been considerable work on the process for reverse flotation of the magnetite concentrates. Ultimately this improves the product for direct reduction. The SiO2 grades in these concentrates may not exceed 1.5%. It is common in Brazil to float quartz from hematite concentrates with relative ease, but the silicates in the magnetite ores of the CMH ore bodies contain only a small proportion of quartz. The main mineral components of the undesirable silicates tend to be rather difficult to float. Extensive tests in mechanical cells and with columns failed.

Magnetic beneficiation has a limited effect in separating silicates from the magnetite, as silicate particles with microscopic inclusions of magnetite are generally recovered, thus contaminating the Fe-concentrate. The analytical test procedure for magnetic assessment uses the Davis Tube, which indicates the values of a theoretical separation but which cannot be obtained in a plant. In Table 9, the results from tests with different flotation techniques are compared (Melendez, 2002). It is obvious that only pneumatic flotation could be feasible.

The designed plant has a capacity of 13,390 t/d of dry mineral feed, with two parallel lines of flotation. Received pulp density is 40% solids (w/w) – slurry SG 1.47 - and a size distribution of 80% -45µm (325 mesh). Secondary amines are used as collector reagents with Methyl Isobutyl Carbinol (MIBC) as frother and starch to depress magnetite. Each flotation line has three 4.5 m diameter pneumatic cells working in series. Each cell works with a compound flow of 756 m3/h containing 50% recycle load. Variable speed pumps are used to feed the aeration units and recycle tailings by controlling the level of slurry in the vessel. Each cell uses this control philosophy while another control loop manages the feed balance to the conditioning tank for each stream and regulates a discharge pump at the end of each line. The flotation circuit represents a new concept of plant design and has a local control cabinet per line with the capability to transfer all process data to the main control room.

- 17 -

Table 9 Comparisons of separation performance.

Components Magnetic

Concentrate Flotation Technology

(feed to flotation) Pneumatic Column Mechanical H H dtt C C dtt C C dtt C C dtt

Fe 68.61 69.64 69.18 69.86 68.67 69.61 69.25 69.76 P 0.021 0.019 0.019 0.015 0.027 0.027

SiO2 2.31 1.56 1.67 1.3 2.08 1.47 1.84 1.6 CaO 0.3 0.22 0.27 0.19 0.3 0.39 0.22 MgO 0.69 0.56 0.66 0.51 0.75 0.63 0.51 Al2O3 0.68 0.63 0.65 0.58 0.74 0.68 0.58

V 0.17 0.15 0.17 0.15 0.16 0.16 0.16 TiO2 0.15 0.11 0.15 0.12 0.11 0.1 0.1

(dtt refers to davis tube magnetic separation)

Table 10 Test results using preconcentrated RD

Material %Fe %SiO2 %Fe dtt %SiO2 dtt

Feed 64.43 3.84 70.50 1.01 Primary magnetic concentrate 69.66 1.54 70.11 1.31 PILOT TESTS Magnetic concentrate 69.92 1.42 70.40 1.28 Peumatic flotation concentrate 70.11 1.09 70.48 1.00 Final magnetic concentrate 70.48 1.06 70.56 1.00

Table 11 Test results using basic preconcentrate

Material %Fe %SiO2 %Fe dtt %SiO2 dtt

Feed 57.99 8.62 70.55 0.96 Primary magnetic concentrate 68.61 2.31 69.64 1.56 Pneumatic flotation concentrate 69.18 1.67 69.86 1.30

- 18 -

Fig. 16 Reverse flotation plant at CMH iron ore concentrator

Fig. 17 General view of CMH concentrator with flotation plant

Discussion and conclusions Ten years of work in the Chilean market with pneumatic flotation demonstrates that Imhoflot technology is a promising industrial alternative. As shown the range of applications is quite diverse, and it is to be expected that these techniques will be increasingly implemented in the

- 19 -

minerals industry in the near future. The main advantage is the capability easily to adapt to the application concerned, and since each cell in the circuit is independent they can be individually optimised. Pneumatic flotation provides a high operational flexibility and can be fully automated. Other benefits include energy, maintenance and investment savings. The high concentration of bubbles and the intensive use of energy provide a flotation cell with fast kinetics, which, using recycling loads, requires compact plant design. As a general conclusion it is clear that the pneumatic flotation is a real competitor to conventional technologies in the market of flotation. References 1- Bahr A., Ludke H, Mehrhoff F., 1982, The Development and Introduction of a New Coal Flotation Cell, Clausthal University. XV International Mineral Processing Congress, 17 – 23 October, 1982, . 2- Barrera V., 1996. Experimental slag flotation results using lab pneumatic pilot tests. Technical Report, Antofagasta, Chile. 3- Fuentes B. G., Espoz A. H., 1995, Incorporación de Nuevas tecnologías de Flotación en

la Planta Concentradora de Minera Michilla S.A. Proyecto de Innovación Tecnológica, Corfo, 1995, Antofagasta, Chile 4- Gonzalez L.R., 2002, Pneumatic Flotation Study as a Pre Rougher Cell at the

Molybdenum Plant. Technical Report, Chuquicamata, Chile. 5- Imhof R.M., 1988. Pneumatic Flotation a Modern Alternative. Aufbereitungs Technik 29: 451 – 458, Weisbaden, Germany. 6- Meléndez Mario, 2002, Uso de Celdas Neumáticas en Flotación Inversa de Fierro

CMP. Taller de Procesamiento de Minerales 2002, Octubre 23-25, Antofagasta, Chile

7- Patent Germany, October 15, 1981; May 5, 1983, Number: DE 314066 A1 Prof. Wolfgang Simonis, et al. 8- Sánchez-Pino S. E., 1990. New Flotation Technology. Mintek Bulletin 31: Johannesburg, South Africa. 9- Sánchez-Pino S. E., 1990. A Comparative Study of kinetics of conventional column and the co-current downwards flotation column. Witwatersrand University, Johannesburg, South Africa. 10- Sánchez-Pino S.E., 1997, Ekof pneumatic Flotation Technology, the alternative for rougher scavenger or cleaner flotation of metallic ores. XX International Mineral Processing Congress, Vol. 3,: 255 – 263, Aachen, Germany. 11- Tapia S. J., 1995, Pilot Pneumatic Flotation Cell Tests, Study as Alternative to the Conventional Flotation Circuit. Technical Report, Cia. Minera Tamaya, Chile.